By Pat Loeb

PHILADELPHIA (CBS) — Closing arguments have ended in the murder trial of Donte Johnson, accused of raping and strangling 20-year-old Sabina O’Donnell near her Northern Liberties home two years ago.

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Faced with DNA evidence, surveillance video, and a confession from their client, the defense made two arguments, one challenging the conclusiveness of DNA evidence and the other claiming diminished mental capacity.

Sperm taken from the crime scene matched Donte Johnson’s DNA to a certainty of one in six billion trillion, but the defense argued that unlikely coincidences are commonplace.

As for the confession, defense attorney Lee Mandel says an expert witness found that Johnson had brain damage of an unknown origin.

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“He didn’t have the capacity, based on the brain damage and his mental health deficiencies, to make that statement and make it voluntarily, as well as the ability to recollect the events that had occurred,” Mandel said today.

That forgetfulness argument drew a sharp rebuke from the prosecutor when it was his turn to speak.  He looked at Johnson and said, “You don’t forget what you did to that girl and you never will.”

O’Donnell was killed during her bike ride home from a friend’s house in June 2010.  Johnson faces life in prison if convicted.

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