According to the Vestmanlands Läns Tidning (VLT) newspaper, a Halloween mask has been found in Kolbäck outside of Västerås in central Sweden.
The tip came to police on Wednesday and the mask will be shown to the boy who was shot.
The 16-year-old was sitting on a park bench listening to music Sunday night when he was shot twice in the neck.
The boy’s injuries were not life-threatening, and the incident is being treated as an attempted murder.
Witnesses heard four shots, but police found several more shell casings in the park.
There have also been several tips on articles of clothing found in Västerås. Witnesses reported seeing a man leaving the area wearing a mask and a hooded sweatshirt, although police are trying to ascertain how exactly he left the scene.
Police are also still searching for a motive to the shooting.
“The motive could be anything. We are open for ideas,” said police spokesperson Börje Strömberg to VLT.