LAKE FOREST, Ill. – The Bears on Monday agreed to a two-year contract extension with defensive end Alex Brown through 2011, released wide receiver Muhsin Muhammad and right tackle Fred Miller, and declined to exercise an option on defensive tackle Darwin Walker, making him a free agent.

Alex Brown is now under contract through 2011 after agreeing to a two-year extension.

Brown finished a strong 2007 season with a flourish. In the final four games, the 2002 fourth-round draft pick from Florida recorded 20 tackles, three sacks, two tackles for loss, one interception, five pass breakups, two forced fumbles and one fumble recovery.

Brown was the only Bears defender to register a sack, interception, forced fumble and fumble recovery in 2007. He rotated into the lineup behind Mark Anderson and Adewale Ogunleye for the first 14 games before starting the final two contests after Anderson injured his knee.

Brown has played in 95 games with 75 starts in six seasons with the Bears, compiling 405 tackles, 31½ sacks, four interceptions, 15 forced fumbles and nine fumble recoveries. The 28-year-old had two years remaining on his contract before agreeing to the extension.

Muhammad departs after catching 40 passes for 570 yards and 3 TDs in 2007. It was his fewest receptions since he had 27 in 1997 in his second NFL season with the Carolina Panthers.

In three years with the Bears, Muhammad caught 164 passes for 2,183 yards and 12 TDs. The 34-year-old was the team’s leading receiver with 64 receptions for 750 yards in 2005 and 60 catches for 863 yards in 2006.

Muhammad signed with the Bears in 2005 after spending his first nine seasons with the Panthers.

Miller started 46 games in three years with the Bears, including 15 in 2007. The 6-7, 314-pounder signed with Chicago in 2005 after spending his first nine NFL seasons with the St. Louis Rams (1996-99) and Tennessee Titans (2000-04).

The Bears acquired Walker last July 29 in a trade with the Buffalo Bills. The 6-3, 294-pounder compiled 33 tackles, one sack and one tackle for loss in 11 games with Chicago.

Walker appeared in 87 games with 75 starts the previous six seasons with the Philadelphia Eagles, recording 264 tackles, 27½ sacks, five forced fumbles and five fumble recoveries.