A man who was pulled over for driving erratically – allegedly with the naked body of his dead girlfriend – told a responding deputy that his “girlfriend may be in the back,” police in Pennsylvania say.

Joseph Sokolowski, 26, of Whitehall, was arrested Wednesday after an alert bystander flagged down an Allegheny County sheriff’s deputy to report a man driving erratically in a van, the Pittsburgh Post-Gazette reports.

Sokolowski stopped his van in the middle of the street and was acting disoriented and apparently under the influence of opioids, Chief Deputy Kevin Kraus said Thursday. Sokolowski was slurring his speech, but denied using the powerful narcotics, telling the deputy he was merely overheated and exhausted.

The windows of Sokolowski’s van were so darkly tinted that the deputy asked him if anyone else was inside the vehicle. After hesitating, Sokolowski said, “My girlfriend may be in the back,” according to a criminal complaint obtained by the newspaper.

The deputy then saw a woman’s naked body lying across the van’s third row seat. The body of Ashley Morgenstern, 32, of Pittsburgh, was already blue and cold to the touch, Kraus said. Attempts to revive her were unsuccessful.

Sokolowski told the deputy he awoke to find Morgenstern unresponsive and then became scared before driving around for several hours. It’s unclear whether Sokolowski awoke inside the van or moved Morgenstern into the van before starting to drive.

“It’s just another tragic example of the opioid epidemic we’re facing in this country,” Kraus said. “It’s almost impossible to control.”

Sokolowski, who was also found in possession of two empty stamp bags, was charged with possession of heroin, abuse of a corpse and driving under the influence, the newspaper reports.

The responding deputy, meanwhile, praised the witness for flagging him down in the first place.

“She came out of her shell to contact law enforcement just by flagging an officer down and telling us about what she saw,” Deputy Sheriff S. Jason Tarap told KDKA.