The 27-year-old was let go two weeks ago by the Dolphins. He told WQAM radio in Miami that he was walking away from the game after six seasons.
Crowder was a starter for Miami since his rookie season but drew criticism for failing to make more big plays. The day after he was released, the Dolphins signed veteran Kevin Burnett as his replacement at inside linebacker.
Last season, Crowder made 33 tackles in 11 games. He missed five games with injuries. Crowder played for the Florida Gators before being drafted by the Dolphins in the third round in 2005.