Evaluation of touch DNA deposited on cell phone screen for forensic purpose

• Grant number: 23/08557-6
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: September 01, 2023
• End date: July 31, 2024
• Field of knowledge: Health Sciences - Medicine - Legal Medicine and Deontology
• Principal Investigator: Cintia Fridman Rave
• Grantee: Juliany Barreto Kisberi
• Host Institution: Faculdade de Medicina (FM). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Fingerprints, evidence often found at crime scenes, have been evaluated using dactyloscopy for about a century. However, with the advancement of procedures and kits used in the forensic area, a new method of human identification has been increasingly used by obtaining STR profiles using the DNA deposited through touch and handling as a source, which is of crucial importance in situations where fingerprints are degraded or not very detailed. This approach is known as Touch DNA or Trace DNA. In the meantime, a new question emerges about what factors could cause the interindividual variations observed in the deposition of this type of DNA, and individuals are now classified according to their ability to donate genetic material via contact, the so-called "shedder status". Historically, this classification only refers to the desquamation of endogenous cells in the hands, disregarding viable sources of DNA, such as sebaceous fluid, present mainly on the face of individuals, which can be transferred to the hands palms and fingers on a daily basis, as well as the differences between the different types of surfaces where this material is deposited. In this context, influences such as age and sex, which may result in different regulations of sebum secretion and epithelial desquamation, should be studied in light of the possibility that endogenous and exogenous sources can be responsible for the DNA deposited via touch. Thus, this project aims to evaluate how the different explicit factors (sebum, age and sex) influence obtaining DNA on cell phone screens, from simulated situations for forensic purposes.