Jason Smith, 36, has been charged with murder and abuse of a corpse in Melissa Ketunuti's death, Philly.com reported.
Police said Smith, who works for an extermination company, made an appointment with Ketunuti at her home the day she was killed.
Smith allegedly told police he attacked her and killed her after an argument.
"During the course of him servicing her, they got into some type of argument," said Capt. James Clark of the Philadelphia police homicide unit. "It went terribly wrong."
That disagreement "escalated into murder," Clark said.
Smith had been spotted on surveillance videotape outside of Ketunuti's home sources told The Philadelphia Inquirer. The sources said he had been working in Ketunuti's neighborhood Monday, the day a dog walker found her body.
Ketunuti's body was in the basement of her row house on a quiet block about half a mile from Rittenhouse Square. She had been tied up, strangled and set on fire, police said.
Investigators searched Smith's house, the Inquirer reported, and could be seen going through the trash cans. His truck was also towed away.
Investigators brought Ketunuti's boyfriend, Dr. Surya Mundluru, a New York resident, to her house to determine if anything appeared to have been stolen.
Ketunuti, a pediatrician at Children's Hospital of Philadelphia, was also working on a master's degree in clinical epidemiology from the University of Pennsylvania.