He later fled the home and was struck by a Chevrolet pickup a block away at Anderson and Pemberton-Browns Mills roads.
A neighbor there said Headley told his mother he murdered Ayres and dumped her body near a soccer field in rural Southampton Township earlier that morning.
"He told her about the murder. He confessed to her. He started running down the street 'cause she called the cops on him," said the neighbor, who asked not to be identified. "He got crushed by that truck. His shoes flew off."
Headley's mother fought back tears yesterday as she stood at the doorway of her small duplex in the Sunbury Village section of Pemberton Township, torn by the brutal crime of which her son is accused. The woman, who did not want her name published, said her son had anger issues and was suicidal when he came to see her Monday night.
She confirmed that she called police after he told her what happened.
Headley's mother said she didn't know Ayres but believed that the woman knew her son through mutual friends and met up at a Wawa. Authorities believe that the slaying occurred early Monday but don't know how the two knew one another.
Headley graduated from the Burlington County Institute of Technology in Medford in 2000.
Ayres lived in Deptford Township. During her four years at Deptford High School, she was a star on the softball team. She dominated from the pitcher's circle, ending her career after surrendering an average of a half-run for every seven innings and a school-record 920 strikeouts.
"She was without a doubt the best pitcher I ever had," said Rich Janofsky, her coach at Deptford, who said he put off retiring to coach the standout for four years. "She worked so hard, helped all the people around her. She had a great personality. It's just terrible what happened"
Softball helped Ayres win a scholarship to Fordham University in New York City, where she was named the Atlantic 10's Rookie of the Year. She left the school after her sophomore year and was enrolled as a sociology major at Rutgers University in Camden. Officials there say she was planning to play on the 2011 softball team.
In Deptford, Ayers' family home on Clifford Avenue was surrounded by cars yesterday afternoon and people milled around the front yard. A woman who identified herself as the victim's aunt told a Daily News reporter and photographer to leave the scene. As the journalists walked away, family members followed, shouting.
"This isn't a news story. This is a tragedy," one yelled.
Matilda Park, a former neighbor and schoolmate of Ayres, said her friend had "never done anything wrong in her whole life."
"She was just an awesome, awesome person," Park, 25, said.
Southampton Township public- works employees found Ayres' body at the end of a dirt road near township soccer fields about 10:30 a.m. Monday. The bloody patch of dirt where she was found had been raked over yesterday.
Headley had not been charged yet when State Police held a news conference yesterday outside their Red Lion barracks, a few miles from the slaying scene. Detective Sgt. Geoff Noble said Ayres had been reported missing to the Deptford police Monday.
Court records show that Headley was sentenced to five years' probation in 2006 on a charge of endangering the welfare of a child, but details of the incident were not immediately available.
After he was hit, Headley was taken by helicopter to the Capital Health System, Fuld Campus, in Trenton. A nurse there yesterday said he was in a procedure and declined to give his condition.
Bail was set at $750,000. Authorities said Headley will have his first court appearance once he's released from the hospital.
Staff writer Natalie Pompilio contributed to this report.