An off-duty police officer in an Illinois village pinned a teenager to the ground and threatened him while accusing him of trespassing, according to a video that the police said they were investigating.

The video, recorded on Saturday by a friend of the teenager, shows the officer in his front yard in the village of Lansing, Ill., a suburb of Chicago, wearing civilian clothes. He appeared to be holding down the teenager with a hand at the boy’s neck. The officer, who is white, can be heard using expletives and saying that he could kill the teenager, Jordan Brunson, 15, who is black.

Jordan’s aunt, LaShawnya Brunson, 42, said she saw the video on Sunday.

She said on Tuesday: “Of course I was disgusted. I was upset. I was angry. I was confused, like why did you do this to this juvenile?”