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COMMON PROBLEMS WITH SPECIMEN COLLECTION WORKSHOP

Saturday 8^th 14.35pm

This workshop will cover common problems encountered with medical samples in sexual offence casework. The presentation will include aspects on sample collection and labelling, sample preservation and useful information to include for the forensic scientist.

Ms Julie McCall

Julie is a forensic biologist at the Victoria Police Forensic Science Centre. She has 18 years of experience in the forensic science area and much of that time has been as a casemanager for various sexual offence cases. She currently head the Sexual Offence casework team.

OVERVIEW

Common Problems in Specimen Collection – Julie McCall

We all naturally shed hair
Clearly fill out associated paperwork
Clearly label specimens: person from / location / date & time / person taking sample
Observe chain of custody
Reference sample buccal swab should be included in the kit along with card and packaged separately from other evidence
Minimum on slides don’t overdo it "a little dab will do it"
Ideally use pencil to write on slides but if ink has been used they will write over it in pencil
Victoria only test slides for semen therefore no point doing "he licked me here" slide
Each swab costs about $400-$500 to process

Common Problems With Specimen Collection- Julie McCall

Leader of the Sexual Offence Team, Victoria Police Forensic Science Centre.

Her presentation was specific for the above center.

There are variations in other States. Clinicians should seek advice from their own laboratory.

The Victorian laboratory tests:

Blood - for its presence, human or not, & DNA
Semen - ditto
Hair - human or not, race, location, previously treated, method of removal.
Skin - for DNA only
Saliva - ditto
Faecal matter, urine & vomit – presence or absence only.

Good communication with the laboratory is essential:

Careful, complete labeling of each specimen submitted – name, location, time, date, person taking the specimen.
Purpose swab taken from that site – eg. History suggestive of contact with semen, saliva or skin.
Continuity (Chain of Custody)

Practical Points re specimens

SLIDES - Label with a pencil. (Methanol used in laboratory process causes ink to run.

A small dab of material on the slide is preferable to spreading widely.
Slides (in Victoria) are examined for sperm only.
SWABS - Allow swabs to dry by cutting off a corner of the container/ tube. - For the same reason do not send in culture medium. Moist swabs become mouldy.

CLOTHING - If clothing cannot be sent dry, ensure they are refrigerated or frozen (same for swabs).

SKIN - In taking swabs from skin, use first a damp swab moistened with sterile water, then a dry swab to mop up the site. Send both to lab marked wet and dry swabs. This gives a better pick-up rate.

PACKAGING It is helpful to package reference samples ( buccal swab &/or blood) separately – either entirely separate or in a separate envelope within a case bag. This may help prevent contamination during the reception process at the laboratory.

Future Directions

Laser Microdissection Systems can identify gender from chromosomes in skin cells. This could prove useful in digital rape investigation.

Summary

To maximise pick-up rate: Label specimens properly; communicate with laboratory adequately; observe practical points with slides and swabs.

Notes taken by: Ifor Thomas