NORRISTOWN, Pa. (AP) - Authorities say they used DNA testing and genealogy research to arrest a teenager in the gunpoint sexual assault of a woman in a suburban Philadelphia park.

Nineteen-year-old Mason Alexander Hall is being held on $1 million cash bail in the August 2017 attack at Norristown Farm Park.

Montgomery County District Attorney Kevin Steele says genetic testing of the DNA helped produce a sketch and showed the suspect had half European and half African ancestry and was about 25 years old.

Steele says that genealogy research led police to identify two people, one of whom was ruled out by the 19-year-old victim.

He says Hall was arrested Friday after the DNA sample was compared to blood found on a hammer still in evidence from his 2017 arrest for allegedly busting a car headlight.

Hall does not have a lawyer listed in court records.

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