The Lions signed free-agent linebacker Bobby Carpenter after a workout following practice Wednesday, a league source said.
Carpenter, 28, was a first-round pick (18th overall) by the Cowboys out of Ohio State in 2006. He was most recently with the Dolphins, where he played in five games with 10 tackles. He was released by the Dolphins on Monday.
Carpenter had his most successful season for the Cowboys last year, when he played in all 16 games and recorded 46 tackles and two sacks.
The Lions also tried out defensive backs Al Afalava and Cord Parks on Tuesday, according to a league source.
The Lions also signed center Cody Wallace from the Jets' practice squad.
Wallace, 6-foot-4 and 300 pounds, spent his first two seasons with the 49ers after they drafted him in the fourth round in 2008 out of Texas A&M.
Wallace, 25, was on the Lions' practice squad earlier this season, but was released Oct. 3. He's played in one career game.
