The Tulalips are the only tribe in Washington to have entered into an interlocal agreement with the County Sheriff (Snohomish County) allowing tribal LE to arrest non-tribal members. If Tribal LE is not willing to fully cooperate in the investigation of such crimes maybe the Island County Sheriff needs to speak with his Snohomish County counterpart about the legitimacy of the interlocal agreement.
_________________________
Remember to immediately record your catch or you may become the catch!

It's the person who has done nothing who is sure nothing can be done. (Ewing)