Touch DNA in a Complicated Alleged Child Abuse Case

Review Article

Austin J Forensic Sci Criminol. 2015; 2(5): 1042.

Touch DNA in a Complicated Alleged Child Abuse Case

Miller Coyle H*

Department of Forensic Science, University of New Haven, USA

*Corresponding author: Miller Coyle H, Department of Forensic Science, Henry C. Lee College of Criminal Justice & Forensic Sciences, University of New Haven, 300 Boston Post Road, West Haven, CT 06516, USA

Received: June 10, 2015; Accepted: December 20, 2015; Published: December 31, 2015


Touch DNA can be of use in establishing what may have occurred through reconstruction of events based on biological evidence transfer. However, interpretation of results and patterns must be approached with some caution as in the alleged child abuse case detailed here. This case was brought forward as a touch DNA and body fluid case where the male in question was a father reported to have forced a young child to perform oral sex on him. Her pajamas were collected and evaluated for presence of body fluids and associated DNA. The sleeves of the pajamas tested positive for amylase, a potential indicator of saliva and DNA of both victim and father combined. Initially, it was thought that this would be clear evidence to bring forth to trial; however, as the remaining stains were tested on the pajamas, reconstruction of events became substantially altered. Up to six family members DNA profiles were recovered off the child’s garments and also a semen stain from a half-brother.

Keywords: DNA; Familial DNA; Touch DNA; Sexual assault; Body fluids; Pattern interpretation


DNA: Deoxyribonucleic Acid; FST: Forensic Statistical Tool; LR: Likelihood Ratio


The enzyme alpha amylase is a non-specific indicator of saliva and was used to screen sixteen stains identified on a young child’s pajama shirt. Of the sixteen stains, six were positive for amylase, two stains were inconclusive, and eight stains were negative. Subsequent DNA testing of the stains revealed various DNA mixtures with at least six family members detected by standard forensic DNA methods. On the pajama pants, fifteen stains were tested for the presence of amylase and seven were positive; one stain was also positive for semen. Alpha amylase is an enzyme produced by salivary glands and using forensic Phadebas tests, false positives have been detected from urine, sweat and fecal matter [1].

Since the amylase diffusion test indicates but is not a conclusive identification for saliva, some interpretation of the DNA profiles associated with the stains was important for forming conclusions about the case. Vaginal secretions and bacteria, both commonly found on worn clothing, also will yield a positive result for amylase [1]. When DNA is recovered from a stained area, it may be from the same source as the body fluid and deposited at the same time as the fluid. Alternatively, deposit may occur as an independent event through touching whereby shed epithelial cells are being placed in the same area either before or after the saliva and appear by DNA test methods as an inadvertent mixture.

Given the accusation of forced oral sex with the juvenile victim, the case went forward for prosecution with the focus being on the two amylase positive stains on the wrist area of the right and left pajama sleeves (Table 1, shirt stains 1 and 2) that contained the DNA mixture of father and victim (shirt stain 1) and victim only (shirt stain 2). However, when the case was evaluated holistically and with a broad overview of all the stains combined with the DNA results, (sixteen on the shirt, and fifteen on the pants) and a surprise semen contributor on the pajama pants, the interpretation of the DNA case became significantly more complex.

Citation: Coyle HM. Touch DNA in a Complicated Alleged Child Abuse Case. Austin J Forensic Sci Criminol. 2015; 2(5): 1042. ISSN : 2380-0801