Julia Law, 26, was found face-down in a bathtub on Saturday in the Center City home of Charles Peruto Jr.
Peruto allegedly told police he was at the New Jersey shore from Friday night through Saturday.
Sources close to the investigation earlier told Action News that there were no signs of trauma and no drugs were found at the scene.
Law and Peruto had been dating for about six weeks.
She was described on social media as someone who studied at Drexel University and worked as a paralegal at Peruto's office.