J. Forens. Sci. Soc.
(1977), 17, 127
Evaluation of Results From Tests Performed on Vaginal, Anal and Oral Swabs Received in Casework ANNE DAVIES Metropolitan Police Forensic Science Laboratory, 109 Lambeth Road, London, England, SEI 7LP Data relating to more than one thousand swabs have been collected over a period of twenty-seven months. The information h a been summarised and assessed.
Introduction When swabs are examined for semen they are subjected to various tests, the results of which are recorded in the case file. In this laboratory from September 1973 until December 1975 these results have also been noted on swab information sheets, which were stored together. This made critical reviewing of the tests possible and provided information which was useful when examining swabs in cases of sexual assaults. In December 1975 it was decided to store the data in a computer, making access easier. This review contains some of the facts that have emerged from studying the information sheets collected. Material and Methods The swabs used by police surgeons to collect samples were made from plain sterile cotton wool. These were tested for blood using the peroxidase test (Glaister, 1926). The presence of acid phosphatase (AP) was detected using sodium a-napthyl phosphate as the substrate, and the diazonium coupling compound diazodiorthoanisidine (Brentamine Fast Blue, B., ICI). The reagents were made up as outlined in a previously published paper (Davies and Wilson, 1974). A smear was made from the dampened portion of the swab on to a piece of filter paper which was then sprayed with the working solution and the time taken for the distinctive purple colour to appear was recorded. (Fast Black K may be used as a substitute for Brentamine Fast Blue B, as it has been found to give similar results when timing the reaction (Wilson, 1976)). The numbers of spermatozoa on each swab were determined by making a smear on a glass slide which was air-dried, heat-fixed and then stained with haematoxylin and eosin. The frequency of spermatozoa was recorded using many in every field; many or some the following symbols: some in some fields, easy to find; hard to find. in most fields; Some swabs were tested electrophoretically to determine the origin of their AP activity (Adams and Wraxall, 1974). This was usually done when a swab was found to have a high,AP activity but no spermatozoa. ABO grouping was carried out, using the techniques of absorption-elution and absorption-inhibition, (Pereira, 1971). The phosphoglucomutase (PGM) typing was performed using Culliford's method (Culliford, 1971).
++
++++
+++ +
Results and Discussion Vaginal Swabs Data from 835 vaginal swabs were recorded on the information sheets. A
third of these swabs were bloodstained, the source of this blood was usually unknown but some must have been menstrual. (It is now customary in all cases involving sexual assault for this laboratory to request that police surgeons state whether victims of sexual assault were menstruating when examined). Just over half the vaginal swabs (423) bore no detectable semen despite the fact that in most cases sexual intercourse was thought to have occurred. The spermatozoa frequencies on the slides from vaginal swabs with semen are illustrated in Figure 1. Just over half the vaginal swabs with semen had a very low spermatozoa frequency and only on a fifth were spermatozoa plentiful.
Spermatazoa frequency Figure 1.
Slide spermatozoa frequency of the 412 vaginal swabs with semen.
The four histograms in Figure 2 demonstrate two facts. One is the correlation between the speed of the Brentamine reaction and the frequency of spermatozoa. The Brentamine test, although biochemically primitive, is a guide to the amount of AP activity and, therefore, to the quantity of semen present. However, also illustrated (histogram d) is the fact that some vaginal swabs with no detected semen gave fast reaction times. I t would seem that a Brentamine reaction time of ten seconds and the development of the typical purple colour is a strong indication of the presence of semen. This is a different conclusion from that drawn from work on vaginal swabs from known donors (Davies and Wilson, 1974). In that paper it was stated that a reaction time of less than 30 seconds was a very good indication of the presence of semen, but 14% of casework vaginal swabs with no detected semen reacted within this time. This is an illustration of the fact that a test cannot be properly evaluated without using casework material. Ninety-seven vaginal swabs with no spermatozoa were tested electrophoretically for the source of their AP. The results are shown in Table 1. There were two instances of banding occurring in unexpected places, namely bands of AP activity in the yeast position from one swab and in the faecal position from the other. Both these swabs were originally thought to bear only vaginal AP. Although neither of the examples cited involved problems in identifying seminal AP, it seems that interpretation of band position is not always straightforward. Grouping in the ABO system was attempted on 226 vaginal swabs (55% of
Rcactio,, time
in, .r.ond.
Rvartian lime in ~rcnnd.
Figure 2. Histograms showing Brentamine spot test reaction times of vaginal swabs with a) , c) and d) no detected spermatozoa. spermatozoa frequency + + + /++ + + , b)
++
+
TABLE 1 RESULTS OF ELECTROPHORETIC TESTING O F ACID PHOSPHATASE ON VAGINAL SWABS WITH NO SPERMATOZOA Brentamine Test Reaction Timet
0-9 10-19 20-29 30-39 40-49 50-59 60
+
Seminal
2 5 1
1 2
11 Total *No yeast visible on slide tSeconds
Electrophoresis Results Vaginal Negative
a 10 13 10 2 10 53
5 6 6 6 1
7 31
Other
1 yeast* 1 faecal 2
those with semen). Reactions for the same group as the victim were obtained from 94 of these (42%). A further 82 (36%) gave inconclusive reactions. Fifty swabs (22%) gave conclusive reactions different from the groups of the victims. The Brentamine reaction time and spermatozoa frequency of these are illustrated in Table 2. (Different figures concerning ABO typing of casework TABLE 2 BRENTAMINE TEST REACTION TIMES AND SLIDE SPERMATOZOA FREQUENCY OF THE 50 VAGINAL SWABS WITH SEMEN GIVING CONCLUSIVE ABO GROUPING REACTIONS DIFFERENT FROM THE VICTIM
Brentamine Test Reaction Times (Seconds) 0-9 10-19 20-29 32
Number of Swabs Reacting within each Time Znterual 26 17 4 2 1 TOTAL 50
80
Slidc S ' t o z o a Frequency
Number of Swabs 1 13 19 f 16 0 1 TOTAL 50 many in every field; many or some in most fields; some in some fields, easy to find; hard to find.
++++ +++ ++
++++ ++
+++ +
vaginal swabs with semen were quoted in another paper (Willott, 1975) but there, the term vaginal swab was used to describe swabs from the vagina and external genitalia. Grouping of swabs from the latter has been more successful). Attempts to type seminal PGM were made on 130 vaginal swabs (32% of those with semen). Fifty-five (42%) gave reactions for the same group as the victim and only 15 (12%) gave reactions for a different group. The latter figure may be unduly low because vaginal swabs from PGM 2-1 victims were TABLE 3 BRENTAMINE TEST REACTION TIMES AND SLIDE SPERMATOZOA FREQUENCY OF THE VAGINAL SWABS WITH SEMEN GIVING A DIFFEREN? PGM GROUP FROM THAT OF THE VICTIM
Brentamine Test Reaction Times (SecondF) 0-9 lei9
Number of Swabs Reacting within each Time Zntewal 12 --
TOTAL
Slide Spermatozoa Fre9uency
3 15
Number of Swabs 1 4 8 2 TOTAL 15 many in every field; many in some or most fields; some in some fields, easy to find; hard to find; 0 absent.
++++ +++ +++
+ ++ + ++
+++ +
not always typed for seminal PGM. The swabs included in this summary were examined before completion of the work by Price et al. (1976) which indicated that the seminal PGM is not necessarily masked by the group of the female. Grouping of semen on vaginal swabs is beset by many problems. These include masking of the seminal groups by the reactions of the vaginal contents, loss of semen from the vagina by drainage and consequent dilution of the remainder by vaginal secretions, and deterioration of at least some of the seminal constituents due to the temperature and composition of their environment. Also the difficulties encountered when grouping blood on cotton wool swabs indicated that these are not ideal for sampling body fluids (Stedman, 1976). The data obtained from the information sheets showed that a Brentamine time of less than 20 seconds was usually required for the successful grouping of semen on vaginal swabs. The reaction time and spermatozoa frequency seemed less critical for ABO typing than for PGM, perhaps because a greater quantity of semen was required for grouping in the latter system. The work of Price et al. (1976) has demonstrated that vaginal swabs should be taken within a few hours of sexual intercourse for successful PGM typing. An attempt is being made to correlate this work which used donor swabs, with casework swabs, by requesting that the length of time between an offence and the swab(s) being taken is amongst the details supplied by police surgeons in cases of sexual assault.
Anal Swabs Data from 357 anal and rectal swabs were recorded on the information sheets. For ease of discussion these were all termed anal. When the results from these swabs were first analysed, anal swabs from the two sexes were considered separately because of the possibility of contamination by vaginal contents of anal swabs from females. However, the figures for both sexes were so similar they were combined. Nearly a third (113) of the anal swabs were bloodstained, almost the same proportion as bloodstained vaginal swabs. Whereas some of the latter were stained with menstrual blood, presumably all the blood on anal swabs was traumatic. Only 94, (26%) of the anal swabs examined, were found to bear semen. The percentage of anal swabs with semen that were also bloodstained did not seem significantly larger than the percentage of anal swabs with no semen that were bloodstained (36% and 30% respectively). The spermatozoa frequencies of the anal swabs with semen are illustrated in Table 4. Over three quarters (74) had spermatozoa that were hard to find and of these a further 31 (42%) had less than 10 spermatozoa on the slide. TABLE 4 SLIDE SPERMATOZOA FREQUENCIES OF ANAL SWABS WITH SEMEN Slide Spermatozoa Fre~ucn~y
++++ +++ ++ %
Numbm of Swabs
1
1 15 (16%)
'
734 (79% TOTAL
94
+ + + + many in every field; + + + many in some or most fields; + + some in some fields, easy to find; + hard to find; 0 absent. The Brentamine reaction was not very useful as a screening test for semen on anal swabs. This was because of the lack of semen on many of these swabs, 131
the usually low level of AP on those with semen and the frequent occurrence of false reactions, many of which gave a swift pinklbrown colour likely to obscure any purple produced by seminal AP. Electrophoretic testing of the AP was carried out on 44 anal swabs with no spermatozoa. The results obtained were: 3 seminal, 13 faecal, 2 vaginal and 26 negative. One of the vaginal results was from an anal swab from a female contents is a possible explanation, but the other . so contamination by vaginal was from an anal swab ti-om a male. ABO grouping was attempted on 23 anal swabs with semen. Two of these gave conclusive reactions different from the victim's group. Both had spermatozoa that were hard to find. One reacted to the Brentamine test within 40 seconds; the other did not react. Reactions for the same groups as the victim were obtained from 12 swabs and a further nine gave inconclusive reactions. PGM typing was attempted on eight anal swabs. Reactions for the same groups as the victims were obtained from four and four were negative. Oral Swabs During this survey 48 oral swabs were examined. Almost half of these (23) were bloodstained. All 23 were from the victims of violent murder. A few spermatozoa were found on three swabs, two of which were from murder victims and one from a living victim of sexual assault. No other constituent of semen was found. Summary and Conclusions Vaginal Swabs Although an unexpectedly high number of vaginal swabs with no detectable semen gave fast reaction times when submitted to the Brentamine test, the timing of the reaction still provided a guide to the amount of semen present and as to whether it was worthwhile attempting to group the semen. Grouping reactions which could be attributed to the semen were obtained from one-fifth of swabs when grouping in the ABO system, and one-tenth when typing PGM. It seems that an AP reaction time of less than 20 seconds is necessary for ABO grouping and less than 10 seconds together with a reasonable spermatozoa frequency for PGM grouping. Anal Swabs Just over one-quarter of those examined bore detectable semen. The Brentamine test was useful only occasionally and spermatozoa were often hard to find. Consequently grouping was rarely attempted and the results were poor. Oral Swabs Spermatozoa were occasionally found on oral swabs from living persons and corpses. In order to provide the greatest amount of evidence, swabs must be taken as soon after the alleged offence as possible. For informed interpretation of results, it is also necessary that the scientist knows the time interval involved. Swabs are not ideal for sampling body fluids and this survey demonstrates a low success rate of grouping semen on vaginal swabs. Therefore grouping of swabs can be sensibly limited, although there will be instances when it should be attempted regardless of the likelihood of success. References ADAMS, E. G. and WRAXALL, B. G., 1974, Forens. Sci., 1, 57. CULLIFORD, B. J., 1971, The Examination and Typing of Bloodstains in the Crime Laboratory, National Institute of Law Enforcement and Criminal Justice, Washington, D.C. DAVIES, A. and WILSON,E., 1974, Forem. Sci., 1,45.
GLAISTER, J., 1926, Br. med. J., 650. PEREIRA,M., 1971, in The Examination and Typing of Bloodstains in t h Crime B. J., National Institute of Law Enforcement and Laboratory, CULLIFORD, Criminal Justice, Washington, D.C. PRICE,C. J., DAVIES, A., WRAXALL, B. G. D., MARTIN,P. D., PARKIN, B. H., EMES,E. G. and CULLIFORD, B. J., 1976, J. Forens. Sci. Soc., 16, 29. STEDMAN, R. A., 1976, Private Communication. WILLOTT, G. M., 1975, J. Forem. Sci. Soc., 15, 269. E., 1976, Private Communication. WILSON,
(1977), 17, 127
Evaluation of Results From Tests Performed on Vaginal, Anal and Oral Swabs Received in Casework ANNE DAVIES Metropolitan Police Forensic Science Laboratory, 109 Lambeth Road, London, England, SEI 7LP Data relating to more than one thousand swabs have been collected over a period of twenty-seven months. The information h a been summarised and assessed.
Introduction When swabs are examined for semen they are subjected to various tests, the results of which are recorded in the case file. In this laboratory from September 1973 until December 1975 these results have also been noted on swab information sheets, which were stored together. This made critical reviewing of the tests possible and provided information which was useful when examining swabs in cases of sexual assaults. In December 1975 it was decided to store the data in a computer, making access easier. This review contains some of the facts that have emerged from studying the information sheets collected. Material and Methods The swabs used by police surgeons to collect samples were made from plain sterile cotton wool. These were tested for blood using the peroxidase test (Glaister, 1926). The presence of acid phosphatase (AP) was detected using sodium a-napthyl phosphate as the substrate, and the diazonium coupling compound diazodiorthoanisidine (Brentamine Fast Blue, B., ICI). The reagents were made up as outlined in a previously published paper (Davies and Wilson, 1974). A smear was made from the dampened portion of the swab on to a piece of filter paper which was then sprayed with the working solution and the time taken for the distinctive purple colour to appear was recorded. (Fast Black K may be used as a substitute for Brentamine Fast Blue B, as it has been found to give similar results when timing the reaction (Wilson, 1976)). The numbers of spermatozoa on each swab were determined by making a smear on a glass slide which was air-dried, heat-fixed and then stained with haematoxylin and eosin. The frequency of spermatozoa was recorded using many in every field; many or some the following symbols: some in some fields, easy to find; hard to find. in most fields; Some swabs were tested electrophoretically to determine the origin of their AP activity (Adams and Wraxall, 1974). This was usually done when a swab was found to have a high,AP activity but no spermatozoa. ABO grouping was carried out, using the techniques of absorption-elution and absorption-inhibition, (Pereira, 1971). The phosphoglucomutase (PGM) typing was performed using Culliford's method (Culliford, 1971).
++
++++
+++ +
Results and Discussion Vaginal Swabs Data from 835 vaginal swabs were recorded on the information sheets. A
third of these swabs were bloodstained, the source of this blood was usually unknown but some must have been menstrual. (It is now customary in all cases involving sexual assault for this laboratory to request that police surgeons state whether victims of sexual assault were menstruating when examined). Just over half the vaginal swabs (423) bore no detectable semen despite the fact that in most cases sexual intercourse was thought to have occurred. The spermatozoa frequencies on the slides from vaginal swabs with semen are illustrated in Figure 1. Just over half the vaginal swabs with semen had a very low spermatozoa frequency and only on a fifth were spermatozoa plentiful.
Spermatazoa frequency Figure 1.
Slide spermatozoa frequency of the 412 vaginal swabs with semen.
The four histograms in Figure 2 demonstrate two facts. One is the correlation between the speed of the Brentamine reaction and the frequency of spermatozoa. The Brentamine test, although biochemically primitive, is a guide to the amount of AP activity and, therefore, to the quantity of semen present. However, also illustrated (histogram d) is the fact that some vaginal swabs with no detected semen gave fast reaction times. I t would seem that a Brentamine reaction time of ten seconds and the development of the typical purple colour is a strong indication of the presence of semen. This is a different conclusion from that drawn from work on vaginal swabs from known donors (Davies and Wilson, 1974). In that paper it was stated that a reaction time of less than 30 seconds was a very good indication of the presence of semen, but 14% of casework vaginal swabs with no detected semen reacted within this time. This is an illustration of the fact that a test cannot be properly evaluated without using casework material. Ninety-seven vaginal swabs with no spermatozoa were tested electrophoretically for the source of their AP. The results are shown in Table 1. There were two instances of banding occurring in unexpected places, namely bands of AP activity in the yeast position from one swab and in the faecal position from the other. Both these swabs were originally thought to bear only vaginal AP. Although neither of the examples cited involved problems in identifying seminal AP, it seems that interpretation of band position is not always straightforward. Grouping in the ABO system was attempted on 226 vaginal swabs (55% of
Rcactio,, time
in, .r.ond.
Rvartian lime in ~rcnnd.
Figure 2. Histograms showing Brentamine spot test reaction times of vaginal swabs with a) , c) and d) no detected spermatozoa. spermatozoa frequency + + + /++ + + , b)
++
+
TABLE 1 RESULTS OF ELECTROPHORETIC TESTING O F ACID PHOSPHATASE ON VAGINAL SWABS WITH NO SPERMATOZOA Brentamine Test Reaction Timet
0-9 10-19 20-29 30-39 40-49 50-59 60
+
Seminal
2 5 1
1 2
11 Total *No yeast visible on slide tSeconds
Electrophoresis Results Vaginal Negative
a 10 13 10 2 10 53
5 6 6 6 1
7 31
Other
1 yeast* 1 faecal 2
those with semen). Reactions for the same group as the victim were obtained from 94 of these (42%). A further 82 (36%) gave inconclusive reactions. Fifty swabs (22%) gave conclusive reactions different from the groups of the victims. The Brentamine reaction time and spermatozoa frequency of these are illustrated in Table 2. (Different figures concerning ABO typing of casework TABLE 2 BRENTAMINE TEST REACTION TIMES AND SLIDE SPERMATOZOA FREQUENCY OF THE 50 VAGINAL SWABS WITH SEMEN GIVING CONCLUSIVE ABO GROUPING REACTIONS DIFFERENT FROM THE VICTIM
Brentamine Test Reaction Times (Seconds) 0-9 10-19 20-29 32
Number of Swabs Reacting within each Time Znterual 26 17 4 2 1 TOTAL 50
80
Slidc S ' t o z o a Frequency
Number of Swabs 1 13 19 f 16 0 1 TOTAL 50 many in every field; many or some in most fields; some in some fields, easy to find; hard to find.
++++ +++ ++
++++ ++
+++ +
vaginal swabs with semen were quoted in another paper (Willott, 1975) but there, the term vaginal swab was used to describe swabs from the vagina and external genitalia. Grouping of swabs from the latter has been more successful). Attempts to type seminal PGM were made on 130 vaginal swabs (32% of those with semen). Fifty-five (42%) gave reactions for the same group as the victim and only 15 (12%) gave reactions for a different group. The latter figure may be unduly low because vaginal swabs from PGM 2-1 victims were TABLE 3 BRENTAMINE TEST REACTION TIMES AND SLIDE SPERMATOZOA FREQUENCY OF THE VAGINAL SWABS WITH SEMEN GIVING A DIFFEREN? PGM GROUP FROM THAT OF THE VICTIM
Brentamine Test Reaction Times (SecondF) 0-9 lei9
Number of Swabs Reacting within each Time Zntewal 12 --
TOTAL
Slide Spermatozoa Fre9uency
3 15
Number of Swabs 1 4 8 2 TOTAL 15 many in every field; many in some or most fields; some in some fields, easy to find; hard to find; 0 absent.
++++ +++ +++
+ ++ + ++
+++ +
not always typed for seminal PGM. The swabs included in this summary were examined before completion of the work by Price et al. (1976) which indicated that the seminal PGM is not necessarily masked by the group of the female. Grouping of semen on vaginal swabs is beset by many problems. These include masking of the seminal groups by the reactions of the vaginal contents, loss of semen from the vagina by drainage and consequent dilution of the remainder by vaginal secretions, and deterioration of at least some of the seminal constituents due to the temperature and composition of their environment. Also the difficulties encountered when grouping blood on cotton wool swabs indicated that these are not ideal for sampling body fluids (Stedman, 1976). The data obtained from the information sheets showed that a Brentamine time of less than 20 seconds was usually required for the successful grouping of semen on vaginal swabs. The reaction time and spermatozoa frequency seemed less critical for ABO typing than for PGM, perhaps because a greater quantity of semen was required for grouping in the latter system. The work of Price et al. (1976) has demonstrated that vaginal swabs should be taken within a few hours of sexual intercourse for successful PGM typing. An attempt is being made to correlate this work which used donor swabs, with casework swabs, by requesting that the length of time between an offence and the swab(s) being taken is amongst the details supplied by police surgeons in cases of sexual assault.
Anal Swabs Data from 357 anal and rectal swabs were recorded on the information sheets. For ease of discussion these were all termed anal. When the results from these swabs were first analysed, anal swabs from the two sexes were considered separately because of the possibility of contamination by vaginal contents of anal swabs from females. However, the figures for both sexes were so similar they were combined. Nearly a third (113) of the anal swabs were bloodstained, almost the same proportion as bloodstained vaginal swabs. Whereas some of the latter were stained with menstrual blood, presumably all the blood on anal swabs was traumatic. Only 94, (26%) of the anal swabs examined, were found to bear semen. The percentage of anal swabs with semen that were also bloodstained did not seem significantly larger than the percentage of anal swabs with no semen that were bloodstained (36% and 30% respectively). The spermatozoa frequencies of the anal swabs with semen are illustrated in Table 4. Over three quarters (74) had spermatozoa that were hard to find and of these a further 31 (42%) had less than 10 spermatozoa on the slide. TABLE 4 SLIDE SPERMATOZOA FREQUENCIES OF ANAL SWABS WITH SEMEN Slide Spermatozoa Fre~ucn~y
++++ +++ ++ %
Numbm of Swabs
1
1 15 (16%)
'
734 (79% TOTAL
94
+ + + + many in every field; + + + many in some or most fields; + + some in some fields, easy to find; + hard to find; 0 absent. The Brentamine reaction was not very useful as a screening test for semen on anal swabs. This was because of the lack of semen on many of these swabs, 131
the usually low level of AP on those with semen and the frequent occurrence of false reactions, many of which gave a swift pinklbrown colour likely to obscure any purple produced by seminal AP. Electrophoretic testing of the AP was carried out on 44 anal swabs with no spermatozoa. The results obtained were: 3 seminal, 13 faecal, 2 vaginal and 26 negative. One of the vaginal results was from an anal swab from a female contents is a possible explanation, but the other . so contamination by vaginal was from an anal swab ti-om a male. ABO grouping was attempted on 23 anal swabs with semen. Two of these gave conclusive reactions different from the victim's group. Both had spermatozoa that were hard to find. One reacted to the Brentamine test within 40 seconds; the other did not react. Reactions for the same groups as the victim were obtained from 12 swabs and a further nine gave inconclusive reactions. PGM typing was attempted on eight anal swabs. Reactions for the same groups as the victims were obtained from four and four were negative. Oral Swabs During this survey 48 oral swabs were examined. Almost half of these (23) were bloodstained. All 23 were from the victims of violent murder. A few spermatozoa were found on three swabs, two of which were from murder victims and one from a living victim of sexual assault. No other constituent of semen was found. Summary and Conclusions Vaginal Swabs Although an unexpectedly high number of vaginal swabs with no detectable semen gave fast reaction times when submitted to the Brentamine test, the timing of the reaction still provided a guide to the amount of semen present and as to whether it was worthwhile attempting to group the semen. Grouping reactions which could be attributed to the semen were obtained from one-fifth of swabs when grouping in the ABO system, and one-tenth when typing PGM. It seems that an AP reaction time of less than 20 seconds is necessary for ABO grouping and less than 10 seconds together with a reasonable spermatozoa frequency for PGM grouping. Anal Swabs Just over one-quarter of those examined bore detectable semen. The Brentamine test was useful only occasionally and spermatozoa were often hard to find. Consequently grouping was rarely attempted and the results were poor. Oral Swabs Spermatozoa were occasionally found on oral swabs from living persons and corpses. In order to provide the greatest amount of evidence, swabs must be taken as soon after the alleged offence as possible. For informed interpretation of results, it is also necessary that the scientist knows the time interval involved. Swabs are not ideal for sampling body fluids and this survey demonstrates a low success rate of grouping semen on vaginal swabs. Therefore grouping of swabs can be sensibly limited, although there will be instances when it should be attempted regardless of the likelihood of success. References ADAMS, E. G. and WRAXALL, B. G., 1974, Forens. Sci., 1, 57. CULLIFORD, B. J., 1971, The Examination and Typing of Bloodstains in the Crime Laboratory, National Institute of Law Enforcement and Criminal Justice, Washington, D.C. DAVIES, A. and WILSON,E., 1974, Forem. Sci., 1,45.
GLAISTER, J., 1926, Br. med. J., 650. PEREIRA,M., 1971, in The Examination and Typing of Bloodstains in t h Crime B. J., National Institute of Law Enforcement and Laboratory, CULLIFORD, Criminal Justice, Washington, D.C. PRICE,C. J., DAVIES, A., WRAXALL, B. G. D., MARTIN,P. D., PARKIN, B. H., EMES,E. G. and CULLIFORD, B. J., 1976, J. Forens. Sci. Soc., 16, 29. STEDMAN, R. A., 1976, Private Communication. WILLOTT, G. M., 1975, J. Forem. Sci. Soc., 15, 269. E., 1976, Private Communication. WILSON,
