Muir, a 30-year-old Lanham native, played high school football at Parkdale in Riverdale where he was an all-state selection as a senior, when he recorded 96 tackles and 13 1/2 sacks.
Muir had 17 tackles and one sack last season for the Raiders in 10 games, including one start. Muir has 128 tackles and 1 1/2 sacks in parts of seven NFL seasons.
He played at Kent State, going undrafted in 2007 after recording 198 tackles, 14 1/2 sacks and 35 tackles for losses in his college career.
The 6-foot-2, 312-pounder has run the 40-yard dash in 4.9 seconds and bench pressed 225 pounds 37 times.