Jim Harbaugh says threatening tweets a 'serious matter'

(Photo: David Guralnick / Detroit News)Detroit — Michigan coach Jim Harbaugh would not say whether he felt threatened by tweets directed at him this week by a former player, but he is confident the matter is being fully investigated.

For the last several days, a stream of menacing tweets have been posted to the Twitter account belonging to former Michigan linebacker Elysee Mbem-Bosse, who has not been on the team since last November. Some included mentions of guns and violent behavior and a potential threat against Harbaugh.

The University of Michigan Police Department opened an investigation into the tweets on Tuesday. Mbem-Bosse has continued to tweet.

“While there has been no crime…