The bodies of two infants possibly used for medical research were found abandoned near a vacant lot in Philadelphia and investigators are trying to determine how they got there, officials said on Monday.
Passersby spotted the deceased baby boy and girl in a patch of grass near a used-car dealership on Sunday and alerted police, the Philadelphia Police Department said in a statement.
The babies, whose exact ages were unknown, had undergone autopsies before they were discovered, a coroner's examination revealed.
The examination also found that the bodies had been medical specimens and were used in some medical capacity at an unknown location, city Health Commissioner spokesman Jeff Moran said. The bodies had been preserved for a long time, Moran said without elaborating.
"We don't know where they came from or how they came to be disposed at that location," Moran said. The time and manner in which the infants died also were not immediately known.
Investigators are pursuing a lead about unidentified occupants of a black pickup truck dumping trash on the highway near where the corpses were located, police said. Police are searching for possible video surveillance footage of the scene.
No arrests have been made and the investigation is continuing, police said.