Autopsy results show that the victim, whose identity has not been determined, suffered "multiple violent injuries, any of which caused her death," state police said in a statement.
Police planned to release more details about the victim, including a likeness of her face.
A state road worker salting I-380 discovered a bag containing the woman's head at about 9 a.m. Tuesday in the median in Coolbaugh Township, Monroe County.
The highway was closed and traffic was diverted as troopers combed the road shoulders and medians. They found at least eight bags containing body parts along five miles of Interstate 80 and 15 miles of I-380 stretching from Stroudsburg to Gouldsboro.
Officials said it is possible there are more body parts, and plan to use a helicopter to assist about 20 troopers on the ground searching for additional remains. An aerial search was called off Wednesday due to high winds, state police Lt. Robert Bartal said.
"We will be continuing (to search) for the next couple of days," he said. "We have a pretty large area."
Police said the victim was white and heavyset, about 5-foot-7, and had dark hair with some gray mixed in. Her remains were taken to Lehigh Valley Hospital, where an autopsy was done Wednesday afternoon.
Police said they are not sure how long the remains had been along the highway. Troopers are reviewing missing persons reports from three states and are also pursuing other leads, Bartal said Wednesday.
