A truck sporting images and messages against Martin Luther King Jr. has drawn the attention of a western Pennsylvania prosecutor.

But the American Civil Liberties Union says the truck — featuring a sign extolling King's assassin, James Earl Ray — along with a Confederate flag and other items is protected speech.

Johnstown police and the Cambria County district attorney's office say they're investigating whether charges of ethnic intimidation might be filed against the truck's owner, who hasn't been publicly identified. Pictures of the truck surfaced on Facebook after it was seen around Johnstown on Monday, Martin Luther King Jr. day.

A sign on the truck's tailgate says, "In Loving Memory of James Earl Ray." A black mannequin was also hanging from the truck.