**Warning: Details of this story are graphic**

OKLAHOMA CITY (KFOR) — A horrible case of animal cruelty in northeast Oklahoma leaves investigators looking for clues to the suspects.

According to police officials in Owasso, two bison were killed on a farm in the area, and a third has been put down due to injuries. Authorities confirm one of the bison had been beheaded.

Owasso deputies say the person who did it knew what they were doing and the head was removed in the correct way to preserve it.

Evidence including fingerprints, shell casings and a knife used in the crime were collected, according to police.