Toni Nelson listened to the sound of her voice making the 911 call and seven years evaporated.

Tears ran down her cheeks, her hand covered her mouth, as the 911 audio tape intoned "June 15, 2008, 1:28.46 a.m.," and then Nelson's voice: "I heard a big bang and he's down. There's a man lying on the sidewalk in front of my house."

So began testimony Wednesday in the trial of Marcellus Jones, charged with slaying 23-year-old Minnesota teaching student Beau Zabel to take his iPod.

Nelson, who then lived at 828 Ellsworth St. in South Philadelphia, testified about that "boom" seven years ago that she said she assumed was an exploding utility transformer on the corner.

"We had problems with the transformer before," Nelson told the Common Pleas Court jury of 10 women and 2 men.

But the moment Assistant District Attorney Jacqueline Juliano Coelho played the audio from Nelson's 911 call, the witness seemed to go into a trance.

Defense lawyer Richard J. Giuliani asked if she recalled the time of her 911 call. She couldn't. He reminded her that it was on the audio recording of the call.

"I wasn't paying attention," Nelson replied. "You have to understand, I'm right back there again. I'm in my pajamas."

On the audio tape, Nelson is heard describing Zabel for the police dispatcher and adding, "He's still down. He's not moving."

Seconds later: "There's another guy out there, he's looking for a bullet. Oh, God, he's searching for something out there."

Nelson testified that she watched the scene peeking between the slats of blinds in her second-floor bedroom. But, questioned by Coelho, Nelson said she could not remember anything about the second man except that he searched for something around Zabel's body and then walked away toward Ninth Street.

Nelson's adult daughter, Sherne, who was on the first floor looking through blinds at the same time, testified that she saw the man searching around the body and described him as an African American who pulled up his white T-shirt over his nose to below his eyes to hide his face.

Jones is African American but neither woman identified him in court as the man they saw.

One other witness, Joseph McCarthy, who lives in the 1100 block of East Passyunk Avenue - a few blocks from the slaying scene - testified that he was watching television when he heard a pop.

Looking out the window of his first-floor apartment, McCarthy said he saw a black man in a white T-shirt and dark pants walking from the area of Eighth Street and Ellsworth rubbing his hands together. A few moments later, as he heard the sound of police sirens, McCarthy said, he looked out his front door and saw the same man walking from the same direction.

McCarthy also could not identify Jones as the man he saw.

The jury watched a mix of grainy video culled from outside surveillance cameras at Capt. Jesse G's Crab Shack at 1101 S. Eighth and Authorized Motor Services at 1112 S. Eighth.

One piece of footage shows a man identified as Zabel stopping at the restaurant, buying a Mountain Dew from an outside soda machine, and walking off.

Other scenes show a man in a white T-shirt and dark slacks walking away from Eighth and Ellsworth seconds after Zabel was shot and killed, and putting an object into an outdoor flower pot. The same man is also seen returning and retrieving an object from the flower pot and hiding it under his shirt.

Jones, 37, of South Philadelphia, is charged with tailing Zabel that night as he walked home after his shift at a Starbucks store at Ninth and South Streets.

Zabel was a teaching fellow enrolled at Drexel University, where, starting in October 2008, he was to teach during the day and take evening courses toward his certificate. In the interim, he got the Starbucks job. Zabel had lived in Philadelphia for just six weeks on June 15, 2008, when he was shot and killed about one block from his home.

Prosecutors have acknowledged that there is no DNA or other physical evidence linking Jones to the shooting, and for years Zabel's slaying was considered a cold case.

Coelho and fellow prosecutor Tracie Gaydos told the jury that Jones incriminated himself through indiscreet admissions to friends and relatives that he was the one who shot Zabel in the back of the neck.

Jones is serving a life prison term without parole for his 2012 murder conviction for shooting Tyrek Taylor, 19, of South Philadelphia.

Prosecutors say that Taylor drove the getaway car for Jones the night Zabel was killed and that Jones later told relatives he killed Taylor because he was talking about Jones' "killing the teacher."

Giuliani has argued that the prosecution case is built on statements made years after the fact, from people desperate to earn favorable treatment from prosecutors and escape long prison terms.