Mathew is a 6-foot-3, 300-pounder who played for the Indianapolis Colts for the past four seasons.
Mathews has played in 52 games with 51 tackles, 1.5 sacks and seven quarterback hits.
Mathews played in every game for the past two seasons and recorded 18 tackles and a half-sack last year.
In 2011, he had a career-high 19 tackles, one sakc, two pass deflections and two tackles for losses.
He's a 2010 seventh-round draft pick from Cincinnati.
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Aaron Wilson covers the Ravens for The Baltimore Sun