From the team themselves:
The Chicago Bears are adding an important piece to their defensive line today with the signing of Akiem Hicks. At 6'5", 324 pounds, Hicks would be a perfect fit for the 5 technique position in Vic Fangio's 3-4 defense. He has the size to play 2 gap, but also the quickness to get after the quarterback. When the Bears go into sub packages, he could be moved inside to rush the passer.
With the New Orleans Saints Hicks started 33 of the 48 games he appeared in, including the first three in 2015 before being traded to the New England Patriots. With the Pats he was a reserve for all 13 games he played in. His total 2015 numbers were 23 tackles, 3 sacks and a fumble recovery that he returned for a touchdown.
His best statistical season came in 2013 with the Saints, when he started all 16 games, making 56 tackles with 4.5 sacks. He is only 26 years old so his best football may be ahead of him.