By Jim Melwert

DOYLESTOWN, Pa. (CBS) — Opening statements were being presented today in the murder trial of a Bucks County man accused of killing a pregnant woman and her four-year-old daughter, then setting the bodies on fire inside a Levittown apartment.

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Bucks County assistant district attorney Matt Weintraub told the jury that four-year-old R’Mani Renkins’ only crime was witnessing the murder of her pregnant mother, 22-year-old Ebony Talley.

Weintraub says he is confident the evidence will show defendant Marcel Johnson was the murderer.

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“A critical piece of evidence was a locket on the floor that the defendant always wore, that had the victim’s blood on it.  There were some drugs stolen from the victim’s apartment that had the defendant’s DNA on it,” he told KYW Newsradio.

But defense attorney Craig Penglase says Johnson sold drugs with the victim, and she often let him stay at her apartment.

He also argues that the car the defendant is said to have used to flee the gruesome murder scene was tested for blood traces and none were found, even though Talley had been stabbed more than 30 times.

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And, Penglase adds, there was no trace of any accelerant even though one was used to try to set the bodies on fire.