Cohen has five years of NFL experience, dividing last season between Dallas and Chicago. He was drafted by Detroit in the seventh round in 2008. Cohen reunites with former Lions coach Jim Schwartz, who is in his first season as Buffalo's defensive coordinator.
Roosevelt rejoins the Bills after spending the 2010 and 2011 seasons in Buffalo. He's a University at Buffalo product and split the past two seasons on the Lions and Cleveland Browns practice squads.