The Chicago Bears secured one of the top pass rushers on the open market, reaching agreement on a five-year, $35 million contract with former Oakland Raiders defensive end Lamarr Houston, sources told ESPN NFL Insider Adam Schefter.

The Bears announced the Houston signing as well as re-signing middle linebacker D.J. Williams to a one-year deal, safety Ryan Mundy to a two-year deal and special teams standout Jordan Senn to a one-year contract.

A disruptive presence who moved to the right side last season in the Raiders' 4-3 base defense, Houston led Oakland with a career-high six sacks, though four came in the season's first seven games.

Houston, who turns 27 on June 24, also led Raiders' D-linemen with 71 tackles (55 solo) and forced two fumbles.

"I'm honored to be joining an organization that has such rich football history," Houston told ChicagoBears.com. "The things that they've already accomplished are something that when you join this organization you hope you can live up to. You know that you're expected to reach certain levels and standards while you're playing for the Bears.

He's not the prototypical edge rusher the Raiders crave, though, and that might be why he said after the season finale that he thought Oakland might move on from him.

Both general manager Reggie McKenzie and coach Dennis Allen, though, had said they wanted him back -- most likely to return to the left side after they pick up that edge rusher either in free agency or the draft.

Williams signed a one-year contract last April worth $1.281 million to replace franchise stalwart Brian Urlacher at middle linebacker. But Williams played in just six games before a torn pectoral muscle on Oct. 10 sidelined him for the season, making way for rookie Jonathan Bostic to join the starting lineup.

Although Bostic showed promise, Bears general manager Phil Emery wanted to re-sign Williams, citing the veteran's leadership as one of the reasons the defense performed well over the first three weeks of the season before injuries started to take a toll.

Williams finished the season with 39 tackles and two sacks.

"I love our defense. It's simple, but we play fast and just downhill," Williams said. "I know I still have a good amount of years left in me. I still have talent."

With Major Wright expected to depart in free agency, the Bears moved quickly to lock up Mundy. Mundy started a career-high nine games for the New York Giants last year where he recorded 70 tackles, one sack and one interception.

Senn is a former Carolina Panther and Indianapolis Colt who can be called upon to replace Blake Costanzo, who is not expected to return to the Bears. Costanzo led the Bears with 17 special teams tackles last year. Senn was named the Panthers' special teams' captain in 2012.

ESPN.com Bears reporters Michael C. Wright and Jeff Dickerson and Raiders reporter Paul Gutierrez contributed to this report.