An Ardmore woman who went missing May 22 was murdered by a man she met on SEPTA’s Market-Frankford El that day and who later dumped her body in an overgrown lot in Philadelphia’s East Germantown section, authorities said Wednesday.

Kareem Malik Davis-Duppins, 26, confessed Tuesday to killing Sabrina DuBose, 25, and led authorities to her body, which was wrapped in a trash bag, Delaware County District Attorney Jack Stollsteimer said. The Upper Darby man has been charged with first-degree murder, abuse of a corpse, and related crimes, Stollsteimer said at a news conference attended by the victim’s family and friends.

Based on statements from witnesses, police believe DuBose and Davis-Duppins met that day as both were passengers on the SEPTA line, the district attorney said.

“They had an interaction from there, a social interaction, that turned deadly,” said Stollsteimer, who called the slaying “a senseless murder.”

Stollsteimer said police from Haverford Township, where the victim lived, and nearby Upper Darby, where they believe she was killed, worked closely to solve the crime.

“Modern technology is a great tool. But it’s actually the hard work of old-fashioned detectives on this case,” he said. “These guys never gave up. When they thought they were looking for a missing person they just kept following every single lead.”

Police were led to Davis-Duppins by cell phone records, video from surveillance cameras outside the train station, a handful of witnesses in whom he confided — including an aunt, an uncle, and a friend who served as a lookout, authorities said, as he moved the victim’s body in a leaking box from the building where he killed her.

The defendant was first confronted by police on May 29 but denied involvement in DuBose’s disappearance, according to charging documents. He was not arrested at that time.

Police believe that DuBose and Davis-Duppins met on the train in Philadelphia, and after they got off at the 69th Street Station in Upper Darby walked to an apartment building at 2 Copley Road, where Davis-Duppins worked as a maintenance man.

In a statement to investigators Tuesday, Davis-Duppins said he and DuBose went into an apartment unit, where he paid her $140 for sexual relations. At some point, according to Davis-Duppins’ statement, DuBose struck her head on a radiator and became unconscious, and when she awoke started screaming that she had been raped.

He then squeezed her neck with his hands until she was dead, and placed her body in an elevator shaft in the building before moving it on May 29 to the lot in East Germantown, the statement said.

Davis-Duppins was being held without bail in Delaware County prison.

Correction: An earlier version of this article incorrectly stated when and where the victim’s body was found.