Park County authorities have asked the Colorado Bureau of Investigation to join the investigation into the slaying of 32 bison from a ranch south of Hartsel.

Park County Undersheriff Monte Gore says CBI likely will concentrate on forensic evidence from the bison carcasses. The animals were owned by ranchers Monte and Tracy Downare but found on the neighboring Hawn Ranch, other private property and federal land.

About a dozen hunters say they had permission to shoot the bison.

The shootings last week occurred just days after Jeff Hawn filed a lawsuit claiming Downare's bison repeatedly broke through fences and damaged his property.

The ranchers have declined to comment.