Phone records and surveillance video from the Center City neighborhood, where Melissa Ketunuti lived, helped detectives track down Jason Smith and charge him with her murder.
Police say the exterminator admitted to strangling the pediatrician from Children's Hospital of Philadelphia and setting her body on fire. A police source tells NBC10 that Smith told them he "just snapped" after having an argument with Ketunuti over his contract.
Investigators took the phone numbers in Ketunuti's phone, and traced people she called with vehicles that were registered to those people. Then they watched surveillance video from the neighborhood to find any matches.
From the surveillance video, police originally identified Smith as a person of interest and then narrowed in on him as the main suspect, before picking him up at his Levittown home on Wednesday night.
Philadelphia Police say before the murder, they saw Smith on video getting out of his truck at 18th and South Street, then walking down 18th Street and onto Naudain Street.
After the murder, police say they spotted Smith on video getting back into his truck, and driving down Naudain Street-- twice.
Smith lived with his girlfriend and small child. Police say he only had minor traffic offenses on his record.