It happened on Jacksonville Road near Almshouse Road in Northampton Township around 6:30 Monday morning.
Northampton police say a 1999 Dodge Caravan ran over 51-year-old Christine Witte.
Investigators say the driver told them he was driving on Jacksonville Road when he hit something.
"Right now he's cooperating with us, he did admit to striking something in the highway but was unsure what it is," said Chief Michael Clark, Northampton Police.
Police say his story is believable because all of the vehicle damage was underneath the minivan.
The driver, who hasn't been identified, proceeded to the Warminster train station and hopped on a train to his Center City office.
After seeing news reports, he called police, who had already located his damaged van.
"Our officers proceeded to pick him up and bring him back," said Chief Clark.
The driver was interviewed by detectives and later released.
Police are certain he ran over the victim but now they're trying to figure out if a crime occurred and if other vehicles are involved.
One theory is Witte had already been hit and was laying in the road.
"There is no damage to the right fender where you'd normally see in a hit-and-run accident. A light, a fender, a windshield, a hood. There's no damage on the vehicle at all, everything is in the center of the car and the very low portion of the car," said Chief Clark.
Detectives are trying to learn why Witte was on the road so early in the morning.
People who had passed by tell police they saw a woman standing near the busy road.
There are no sidewalks and there is little shoulder space.
The accident happened right in front of the home Witte shares with a parent.
Meanwhile, police expect to learn more after an autopsy is completed. The results are expected in the next few days.
Anyone with any information is being asked to call the Northampton Police Department.