As 14-year-old Nathaniel Wells recalled, "We started busting on them."

It was Wells and two teen boys on one side of 19th Street in South Philadelphia and two teenage girls on the other, taunting each other about looks and clothes.

It was harmless until it wasn't, when 14-year-old Azim Chaplin looked up and said: "I'm stabbed."

"I lifted up his shirt and just saw blood," Wells said.

Wells' testimony on Tuesday persuaded a Municipal Court judge to order 15-year-old Amber Hellesten to stand trial on a charge of third-degree murder in the Feb. 11 stabbing that killed Chaplin in a confrontation in the 2100 block of Watkins Street.

Judge James M. DeLeon seemed troubled about Wells' testimony and said Hellesten might be able to argue that she killed Chaplin in self-defense.

"She might have been OK if this were Florida, with 'stand your ground,' " DeLeon told defense attorney David E. Desiderio. "But we're in the Commonwealth of Pennsylvania."

Desiderio had argued that charges against his client should be dismissed, citing testimony that Hellesten stabbed Chaplin after he and two friends followed her and a girlfriend for 51/2 blocks, taunting them and throwing ice and snowballs.

Finally, Desiderio said, the six-foot, 127-pound Chaplin confronted the shorter Hellesten, holding a stick over his head.

Hellesten pulled a folding pocket knife from her coat and stabbed Chaplin once. The blade went between his fifth and sixth ribs and punctured his heart. Chaplin died five days later.

Assistant District Attorney Gwenn Cujdik argued that Hellesten should be tried for murder because she took a common case of "teenagers being teenagers" and turned it into a homicide by overreacting.

After holding her for trial on a third-degree murder charge, DeLeon reduced Hellesten's bail to $150,000, an amount Desiderio said her family might be able to raise.

Desiderio said he would also move to have Hellesten's case moved back to Family Court so she can be tried as a juvenile.

The District Attorney's Office can move a minor's criminal case into the adult court system. After Hellesten is formally arraigned May 13, Desiderio may petition a Common Pleas Court judge to have her case returned to Family Court.

Desiderio said Hellesten had been assaulted before and had a history of mental illness, which may explain why she carried a knife and reacted as she did to Chaplin.

Cujdik's only hearing witness was Wells.

As the banter became more barbed, Wells said, he and the other boys began throwing snow and ice at the girls until Hellesten turned and told Chaplin she was going to call her brother and "have [Chaplin] killed."

Hellesten and her friend turned onto 20th and headed south, Wells continued, and he and his friends followed them until the fatal confrontation on Watkins.

DeLeon seemed incensed by Wells' testimony. "This is a confrontation that went on for 51/2 blocks," the judge said. "You just don't be following strangers and busting on them. This is like gang activity."