COLORADO -- Police believe a Colorado prison chief's murder could be gang related.

Just days before he died, Tom Clements believed a white supremacist gang was getting too strong in the prison so he tried to break them up.

Now investigators are interviewing inmates, to see if anyone ordered a hit.

"A lot of these guys deal with the element of fear," said Reverend Leon Kelly, parolee gang reform leader.

"They have devised all kinds of codes... so they might send out a letter that looks like a quite benign letter but is actually directing a hit or some other kind of criminal activity," said Mark Potok, Southern Poverty Law Center.

Many prisoners respected Clements.

This week's parolee graduation will be dedicated to his honor.