"Cash-Strapped Michigan Sheriff's Department Auctioning Machine Gun"
UPDATE: Sayuncle writes me that:
There have been two murders committed with lawfully owned MGs. One case was a cop used a Mac 10 to murder an informant. In another, a wealthy doctor killed his assistant whom he'd been stalking with a Mac-10.
UPDATE: Sayuncle was nice enough to inform me that the case involving a police officer did not involve a privately owned machine gun. He pointed to the details are available here.