DNA Evidence Helped to Create Composite of Alleged Rapist
Click to enlarge. | MCPD
Detectives investigating an October rape have used the services of a Virginia company that can predict a person’s physical appearance and ancestry through unidentified DNA evidence, a Montgomery County police statement said.
The statement, released Wednesday, said Parabon NanoLabs uses what is called DNA phenotyping to produce a composite depicting how the person sought in the case could look.
The rape occurred about 5:30 a.m. Oct. 6. A woman was waiting for a bus at a Gaithersburg bus stop on Watkins Mill Road and Travis Lane when she was approached by the rapist, police said.
The man, in his 20s and wearing a dark-colored, checkered shirt or jacket, acknowledged the victim’s presence, police said. He then grabbed her and pulled her toward a wooded area next to the bus stop, police said. The man then raped the victim and fled, police said. The woman ran from the area and called police.
Police said Parabon’s DNA phenotyping service used the DNA contained in the body fluids left by the man to produce trait predictions. Individual predictions were made for the subject’s ancestry, eye color, hair color, skin color, freckling and face shape.
By combining these attributes of appearance, composites were produced depicting what the suspect might look like at a certain age and with a certain body-mass index, police said. The default ages and default BMIs were used because age and BMI cannot be determined from DNA.
The service costs $3,500, Officer Rick Goodale said.
Police said the composites are scientific approximations of appearance based on DNA, and are not likely to be exact replicas of appearance. Environmental factors such as smoking, drinking, diet and other non-environmental factors — e.g., facial hair, hairstyle, scars, etc. — cannot be predicted by DNA analysis and may cause further variation between the subject’s predicted and actual appearances.
The hair style for the composite came after interviewing the victim, Goodale said.
Montgomery County police have used Parabon at least twice in the past: for a series of rapes that took place from June 2010 to September 2012, and to help solve a 1992 homicide.
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