An argument with an exterminator led to the brutal strangulation and burning death of young pediatrician at her Philadelphia home on Monday afternoon, police Capt. James Clark said at a news conference Thursday.

Jason Smith, 36, of Levittown was taken into police custody at 9 p.m. Wednesday. He was formally charged with murder, abuse of a corpse, arson, and causing/risking catastrophe on Thursday morning.  

The burning body of 35-year-old Melissa Ketunuti was discovered by her dog walker at her Naudain Street home Monday. Her wrists and ankles had been bound.

“She had been strangled to death, and her body had been set on fire,” Clark said.

During the course of an intensive investigation by the homicide unit, authorities said they found surveillance video of Smith on Ketunuti’s block about an hour before her body was discovered.

Investigators say Ketunuti had called an exterminator service earlier that day because of rodents in her home and Smith, a subcontractor, was dispatched.

“During the course of him [Smith] servicing her, they got into some type of argument. It went terribly wrong,” Clark said. “At that point, he struck her while she was in the basement, knocked her down, strangled her to death and then ultimately set her body on fire.”

Smith used a rope in the basement to strangle Ketunuti and possibly set the body on fire to hide evidence, according to Clark.

"You have a young physician who dedicated her life to helping people and, to have her die in this manner is very sad," Clark said.

In 2008, Ketunuti moved from Washington D.C. to Philadelphia, where she was a pediatrics resident at the Children’s Hospital of Philadelphia.

“Melissa was a warm, caring, earnest, bright young woman with her whole future ahead of her,” Dr. Paul Offit, chief of the hospital’s division of infectious diseases, said in an e-mail statement Tuesday.

“But more that that, she was admired, respected and loved by those with who she worked here…Her death will have a profound impact on those who worked wit her and we all miss her deeply.”

HLN attempted to locate an attorney representing Smith, but the Defender Association of Philadelphia was unable to assist.