Detection of touch DNA evidence on swab by SYBR®Green I Nucleic Acid Gel Stain.

Invisible touch DNA sample is one of the most common sample types received in the DNA laboratory. However, the appearance of DNA from touch sample collection cannot be observed until the DNA detection process is completed. The objective of this study focused on effectiveness of SYBR®Green I Nucleic Acid Gel Stain (SYBR Green I, Invitrogen, USA) using four types of swabs; including cotton, rayon, nylon, and foam swab, for collecting touch DNA from objects. Touch DNA samples were collected from 1 male and 1 female volunteers and stained with 5x SYBR Green I. This study demonstrated 3 experimental designs; including effectiveness, stability and visualizing of touch DNA mockup study. The results showed that the foam swab was the only swab type that could distinguish between touch DNA with and without SYBR Green I fluorescence; therefore, the foam swab was studied in the mockup experiment step and was appropriate for the study of the stability of SYBR Green I stained swab. Furthermore, our results on stability study showed that touch DNA on foam swab stained with 5x SYBR Green I fluorescence immediately faded on Day 1 , but remained until Day 28 in the dark at room temperature. The mockup study using a foam swab that collected touch DNA on objects and stained it with 5x SYBR Green I revealed that SYBR Green I fluorescence was visualized differently from that without touch DNA. These outcomes indicated that SYBR Green I can be used as a stain in the touch DNA screening method on foam swabs for forensic laboratory, which would increase productivity by reducing time and resources cost.

Sacral morphometrics for sex estimation of dead cases in Central Thailand.

Sex estimation by various forensic anthropology approaches is a crucial factor for identification of human skeletal remains. However, inexpensive, uncomplicated and reliable methods are still required, especially in a remote crime scene and a high crime incidence area. Here, we examined 13 sacral parameters from 78 independent skeletons derived from deceases found in Central Thailand (male, n = 46; female, n = 32) using simple standard anthropometric techniques for sex allocation. Discriminant analysis exhibited that anterior-posterior diameter of S1 vertebra corpus (APS) is the most accurate sacral parameter for sex determination in our study with 82.1% of correct discrimination rate. The accuracy could be improved up to 97.4% when additional three sacral variables including the length of sacrum measured from the medial anterior-superior sacral promontory to the medial anterior-inferior S5 vertebra (ASL), alar index (ALI), and the maximum anterior breadth of sacrum measured across sacral alar (ABS) were computed together with APS. These encourage the use of sacral morphometrics for sex assessment of human sacrum remains in Central Thailand. However, further investigation with broadening sacral morphometric data across the country might provide a promising sex determination equation from a sacral skeleton for Thai population.