Forensic Update Nicola Clayson Lead Scientist Sexual Offences

Forensic Update Nicola Clayson Lead Scientist – Sexual Offences and Damage SPA Forensic Services, Edinburgh nicola. clayson@spa. pnn. police. uk

• Outline the work undertaken at the forensic laboratory. • New techniques. • Casework considerations.

Scientific Investigation of Sexual Offences • • Semen Vaginal Material/Cellular Material Blood Saliva Faeces Urine Fibres/Hair Damage to clothing

Acid Phosphatase (AP) • Test for seminal fluid • Strength & speed of reaction

Microscopic Examination The spermatozoa found are scored using the following guidelines: • 2µl aliquot of pellet • Differential stain (H&E) + heads - hard to find ++ heads - easy to find with some heads in some fields +++ heads - many or some heads in most fields ++++heads - many heads in every field The presence of tails is also noted.

DNA Profiling – SGM +

DNA Profiling – Globalfiler

• 24 areas, including mini. STRs • Better performance on inhibited and lowlevel samples • Twice as sensitive

Semen Persistence • • Vagina Anus Mouth Skin • Clothing up to 7 days up to 3 days up to 2 days subject to abrasion/ reduced by washing AP until washed Spermatozoa after washing • All relevant swabs should be taken in line with the FFLM guidelines. • Guidelines are reviews every 6 months, critical as DNA chemistry changes.

Azoospermic and Oligospermic Semen • • AP reaction Choline DNA profiling Semenogelin

Case Example • • • Girl walking through park and befriended by young male. They spend a couple of hours together chatting. The male then takes the girl to a secluded area removes her lower clothing and rapes her. Incident reported to Police and girl is medically examined less than 12 hours later. Girl has not washed and no previous intercourse. Biology Exam • Vaginal swabs from girl - semen present and submitted for DNA analysis DNA • Male DNA profile obtained. If no suspect, profile can be uploaded to National DNA Database. If further enquiries lead to a suspect a buccal swab can be taken for DNA analysis for direct comparison with profile already obtained.

“Vaginal” Material • Penile Swabs • Condoms • Nail / finger swabs • Clothing e. g. men’s underpants • Mixtures e. g. bedding, inserted objects

Case Example Female child complainer. • Accused lived next door. Numerous allegations made against accused in previous years. • Complainer stated that accused had digitally penetrated and raped her. • Accused denied any sexual contact. Biology Exam • Internal and external vaginal swabs from complainer – no semen found. • Clothing submitted had been washed – extracted crotch of complainer’s pants – 10 sperm heads found. Submitted for DNA • DNA from sperm heads on pants matched accused. N. B. Case dependent!

Case Example • • Uncle had been sexually abusing his niece over a long period of time. When it was reported to the police the last incident had been over 3 weeks previous therefore no medical swabs taken The girls bedding was seized as it hadn’t been washed for over a month. Bio Exam • Sheet screened for semen using AP reagent. Two areas of semen staining found and submitted for DNA Exam • Both areas of staining were a mixture of the Uncle and his niece Issues • Uncle has stayed over at his brothers house (niece’s father) a few times over the last month and had been given his niece’s bed to sleep in. • We are unable to say when the semen was deposited in the bed, other than since it was last washed. • We are unable to say whether the stain could be due to a semen stain deposited on top of the sheet where the niece’s DNA was already present rather than an actual mix of two body fluids

Case Example • Young boy at his friends house is left alone with his friends older brother. The brother forces him to perform oral sex on him. The brother ejaculates in his mouth. • The victim runs home and brushes his teeth and rinses his mouth out with water a few times. • He then tells his parents and it is reported to Police and medical exam carried out. The suspect is found next day and is medically examined. He hasn’t washed. Biology Exam • Cells on penile swabs - submitted for DNA. No Saliva test carried out. • Victims toothbrush is taken and examined. Traces of semen found. DNA Exam • Mix of victim and accused DNA from accused penile swabs. • Accused DNA from semen found on toothbrush

Semen Considerations • When was the semen deposited (bedding, underwear). • Effect of washing (traces of semen found on jeans taken 1 year after the incident date). • Contact with items potentially stained with semen (washing basket, washing mahine).

Saliva • • Oral sex - penile swabs / condoms Licks, sucks and bites Spitting Chewing gum

Tests for Saliva • Saliva - High concentration of Amylase • Not everyone produces amylase, and it is present in other body fluids. • Phadebas test – indicator only, not conclusive • Microscopy – mouth cells • DNA

Other Items • • • Tampons Condoms Clothing Bedding Objects inserted Toothbrushes

Touch samples / contact traces • Generally no suspect cases – no other evidence • Swabs of waistbands, buttons / zips, anywhere complainer was grabbed • Elimination samples from anyone involved

LASER MICRODISSECTION (LMD)

Damage to Clothing • Important in consent cases • Age of damage – old, recent, not determinable • Physical fit • Type of damage • Compare to weapons • Amount of force? – v. difficult, many variables

Scenes/ Larger Items • Clothing • Bedding • These items can be submitted to the laboratory for exam. • Seating • Floors • Cars • Other items may require scientists to examine them in situ.