Vikings sign backup LB Marvin Mitchell

The Minnesota Vikings have signed linebacker Marvin Mitchell. The deal was announced Tuesday on the team's website. Terms were not disclosed. Mitchell was a seventh-round draft pick by New Orleans in 2007 who spent four seasons with the Saints and last year with Miami. He had 30 tackles, two forced fumbles, one sack and one interception last season for the Dolphins. The 27-year-old has played primarily on special teams, but the Vikings have been seeking linebacker depth behind Jasper Brinkley, Chad Greenway and Erin Henderson. The Vikings have been gradually turning over their defense this spring by adding lower-profile free agents. Last week, they signed cornerback Chris Carr, most recently of the Baltimore Ravens.