The San Diego Chargers announced the singing of third-round linebacker Donald Butler, and confirmed the signing of fifth-round defensive tackle Cam Thomas, which was reported here first.

Financial terms of the four-year deal were not disclosed.

Butler (6-1, 245) was a two-year starter at the University of Washington, and is coming off a breakout season where he led the Huskies with 94 tackles, 15.5 of which came behind the line of scrimmage. Butler also added a pair of interceptions, returning one for a touchdown.

Butler had an impressive showing at the 2010 Senior Bowl, and while he was unable to fully workout at the 2010 Scouting Combine, he impressed scouts and talent evaluators by doing 35 reps on the bench press, tops among the linebackers. At his pro day on March 10, Butler ran a 4.61-40, and showed off his athleticism with a 35.5" vertical leap and 10'01" broad jump.

Because Washington is on the "quarters" system, Butler missed most of the Chargers off-season workouts and is a bit behind of the rest of team heading into training camp. Butler is expected to improve their depth at inside linebacker, and press for a starting job in 2011. His primarily role this season will be on special teams.