Research Information System
Thesis Type: Expertise In Medicine
Institution Of The Thesis: Hacettepe University, Tıp Fakültesi (Türkçe), Dahili Tıp Bilimleri Bölümü, Turkey
Approval Date: 2021
Thesis Language: Turkish
Student: BURAK TAŞTEKİN
Supervisor: Ramazan Akçan
Abstract:
Body fluids such as blood, semen, vaginal secretions, and
saliva are frequently encountered at the crime scene. In sexual assault crimes, one of
the most reliable biological evidence is semen stain. Age determination of the semen
stain plays an important role in both confirming sexual assault, identifying suspects,
and estimating the time frame in which the crime occurred. It is aimed to develop a
method to determine the time of formation by using Attenuated Total ReflectionFourier Transform Infrared (ATR-FTIR) Spectroscopy for up to 8 weeks in semen
stains dripped on five different fabric types. High R2
values and low root-mean-square
error (RMSE) were obtained in models constructed using Principal Component
Analysis (PCA) and Partial Least-Squares Regression (PLSR). Although it varies
according to fabric types in modeling, it has been observed that age estimation can be
made with an interval between 0.18-0.32 days in the range of 0-3 days, between 0.56-
1 days in the range of 3-7 days, between 2.66-3.96 days in the range of 1-4 weeks,
4.74-6.56 days in the range of 4-8 weeks. In this thesis, it has been shown that ATRFTIR spectroscopy combined with chemometrics can be an effective method for
estimating the age of human semen stains on different fabric types based on timedependent changes in the spectrum.