Maryland police have a man in custody and syringes full of semen^[1] in evidence after a bizarre attack^[2] at a grocery store last month, when the suspect allegedly injected something into an unsuspecting woman’s buttocks.

Thomas Bryon Stemen, 51, is facing charges of first-degree assault, second-degree assault and reckless endangerment in connection with the Feb. 18 incident, the Anne Arundel County Police Department said in a news release^[3]. Stemen was arrested last week after police released footage of a man appearing to jab a woman in the buttocks with a syringe.

Police say syringes recovered during the arrest have tested positive for semen.

“The substance in the syringe was semen,” police said in an update to their initial press release on Saturday^[4]. However, they later told local station WJZ^[5] that they’re not certain whether they’ve recovered the actual syringe used in the attack.

“We are unsure if any of those were the syringe in question,” police told the station in what they said was an update to their initial statement. They say the victim is still undergoing testing.

“We need to find out … what this victim is up against, if she was stabbed with one of those semen-filled syringes,” Anne Arundel County Police Sgt. Jacklyn Davis told the station.

Security footage shows the moment when Stemen allegedly stabbed the victim, Katie Peters, with a syringe at the entrance to Christopher’s Fine Foods in Churchton, Md.

In the video, Peters pushes a shopping cart into the store and returns it to the lineup of empty carts, seemingly unaware of the suspect following a few paces behind her. He can be seen holding a cylindrical object in one hand. The suspect walks behind Peters, pivots and appears to jab her in the buttocks with the object, which police say was a syringe.