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RIDGWAY - An expert forensic DNA scientist testified on Thursday, during day four of the homicide trial of Lawrence Earl Donachy, 36, who is charged in the April 5 or 6, 1999 death of Irene Challingsworth, a St. Marys beautician. The trial is being held at the Elk County Courthouse in Ridgway.
Pennsylvania State Police Forensic DNA Scientist Alex Glessner, employed for the past 10 years at the PSP Greensburg lab, provided extensive information on DNA profiling pertinent in the case.
Glessner explained that DNA is found in all cells within the body except for red blood cells. It is made up of two halves, one half belonging to the mother and the other half belonging to the father. He said DNA controls everything in the human body, such as eye color, hair color and chemical processes which take place in cells, and most importantly, can be used to identify individuals because it is specific to each person.
The Greensburg lab specializes in short-tandem repeats, or STR testing, a process used in developing a DNA profile within 16 areas. Fifteen of the areas measure lengths of DNA, with the 16th area determining a person's gender.
Glessner noted the well-established STR method has been utilized by labs around the world since the 1990s and is also used in medicine and research.
He testified that on January 28, 2003, he tested two vaginal swabs from Challingsworth sent from the PSP Erie Crime Lab. Glessner was requested to develop a DNA profile from the swabs.
Glessner said he observed a yellowish discoloration on the swabs, as well as portions missing which had already been tested by serology as part of the study of bodily fluids.
With the remaining material on the swabs, Glessner extracted DNA, which resulted in two different profiles found on the swabs.
On February 27, 2003, Glessner said the conclusion was made that the male sperm fraction sample obtained from a vaginal swab matched the male sperm fraction obtained from a semen stain found on a fitted sheet collected from Challingsworth's bed where her body was found.
This male sample was then entered into the DNA index system.
Glessner explained PSP obtained a buckle swab, where cells are collected from the inside of a subject's cheek using a Q-tip-type swab, from Donachy in 2008.
He noted a buckle swab is a common and easy method in obtaining DNA and replaces the method of collecting an individual's blood sample.
He said PSP Trooper Agosti hand-delivered the buckle swabs to Glessner on Feb. 19, 2008. The buckle swabs underwent the same testing process as the other evidence.
Glessner testified that the DNA profile obtained from Donachy's buckle swab matched the profile obtained from the vaginal swab and bedsheet semen stain.
He emphasized the probability of randomly selecting a person which would match the profile is 1 in 20 quadrillion from the Caucasian population.
Glessner said there were no issues or abnormalities during testing.
The trial resumes at 9 a.m. Friday morning.