A month after she buried her parents and aunt in the Dominican Republic, Jessica Nunez came home to Philadelphia. She had a promise to keep.

She cut off her hair to disguise herself. And then she went back to work at the family bodega at 50th and Parrish, where her family members had been shot to death in front of her.

Time passed. She took a job at another bodega in the West Philadelphia neighborhood, then another, scanning customers' faces as they bought chips and lottery tickets. In her spare time, she staked out the other corner stores in the neighborhood, sitting inside for hours, waiting.

Nunez had promised her family that she would find the killers. She wanted to be there if they walked through the door.

Nunez, who was 19 at the time of the killings, testified Wednesday in Common Pleas Court that Ibrahim Muhammed and Nalik Scott, both 35, were the gunmen who burst into Lorena's Grocery on Sept. 6, 2011, demanding money. Porfirio Nunez, 50, his wife, Juana Nunez, 44, and his sister Lina Sanchez, 48, were killed.

Jessica and her younger sister Laura, 17 at the time, were working the cash register during the robbery, and survived. Jessica's testimony will continue Thursday, with Laura's expected to follow.

Muhammed and Scott's attorneys, Larry Krasner and Jack McMahon, say their clients are innocent, the victims of mistaken identity.

Investigators said in 2012 that they had linked two bodega robberies prior to the Lorena's Grocery killings. A few days later, Muhammed was arrested on an unrelated drug charge, and he offered information on other crimes. He was sent to Southwest Detective Division for an interview, prosecutors said, where investigators talked to Muhammed and suspected he had been captured on video during one of the earlier robberies.

Muhammed was subsequently sent to the homicide unit, where police said he confessed to the murders and robberies.

Krasner said in his opening argument Tuesday that the confession was false, taken while Muhammed was off his medication for schizophrenia.

And Scott, McMahon said, became a suspect only after Muhammed named him in his confession.

The jury listened Wednesday to hours of harrowing testimony from Jessica Nunez, who provided the first eyewitness account of the horror that transpired inside her family's bodega.

On the stand, she sobbed as she recounted how she and Laura had screamed for their father in the first moments of the robbery. One of the gunmen grabbed Laura's hair and pushed a semiautomatic handgun into Jessica's side.

Porfirio had come running. Her father had his own gun in his waistband, Jessica said, but he never had a chance to draw it.

"Please wait," she said he told the gunman, whom she identified from the stand as Scott.

The man shot her father.

In the back of the store, Jessica said, she heard a second gunman, whom she identified as Muhammed, firing at her mother and aunt, near the deli counter. Her father, clutching his shoulder, staggered back toward the deli counter.

"I know he was trying to save my mother and my aunt," Jessica said, "and he couldn't do anything."

Then the second gunman emerged from the back, she said, pointing the gun at her.

"I thought he was going to kill me," she said. "I just stood quiet." Instead, the men ran from the store with several hundred dollars from the cash register and lottery machine, she said.

When they were gone, Jessica said, she told her younger sister that their parents were dead.

"In less than two minutes," she said, "I didn't have a family."

Prosecutors called several witnesses from the neighborhood Wednesday who described a pair of men they had seen in the area before and after the murders. Those witnesses were not asked to identify the men in photo arrays because they told police they could not positively identify them.

In hours of cross-examinations, defense attorneys argued that witnesses' descriptions did not match the defendants, building a case for mistaken identity.

Even a prosecution witness said he had hesitated before stepping forward because he feared being considered a suspect.

"We know mistaken identity happens all the time. We live in Philly," one prosecution witness told McMahon under cross-examination. The witness, a firefighter whose mother lives in the neighborhood, said that minutes before the shootings, he saw two men cross 50th Street near the bodega.

He explained that he had called police later to report what he saw because he "knew how things can get turned around" and "didn't want to get caught up in anything I wasn't a part of."

McMahon challenged several witnesses, including Nunez, on the appearance of the suspects. In her initial police statement, Nunez had said the gunman who held her and her sister at the front of the store was 5 feet 4 inches tall. Scott, McMahon said, was 5 feet 10 inches tall.

And several witnesses didn't say the second gunman had any facial hair, McMahon said. Muhammed has had a beard since he was a teenager, he countered.

Nunez worked bodega jobs for several months before Muhammed and Scott were arrested.

She told the jury Wednesday that she had seen a few men who looked like the killers.

Once, during one of her shifts, she saw a man who looked so much like Scott that she called police in a panic, asking them to find the man and interview him.

Krasner said in his opening arguments Tuesday that police had reviewed surveillance footage from that bodega and identified the man who frightened Nunez as a member of a local crime ring. He suggested that man, not his client, could be the killer.

He said investigators dropped the lead when Muhammed confessed, a few days after Nunez called about the man in her bodega.

But Nunez said on the stand that she called police because she thought the man she saw was Scott's relative, and might have information on the case.

She was adamant that the defendants were the men who had killed her family. "Do you have any doubt that's him?" prosecutor Carlos Vega said, pointing to Muhammed. "Do you have any doubt it was Scott?"

"None," she said firmly.

215-854-2961@aubreyjwhelan