Schweigert, a third-round pick out of Purdue in 2004, became the starter at free safety midway through his second season in Oakland and started 37 consecutive games before being replaced last season.
Schweigert lost his job to Hiram Eugene when he was forced to miss a game with an injured calf and then played as a backup in the final five contests of the season.
Schweigert struggled at times last season as a run-stopper and the Raiders set out to improve their tackling at safety this offseason by signing Gibril Wilson from the Super Bowl champion New York Giants.
Wilson lined up mostly as a strong safety during last week's practice open to the media, with former first-round pick Michael Huff shifting to his more natural position of free safety. That left little room for Schweigert, who missed the open practice with a leg injury.
Schweigert had 215 tackles and four interceptions in 63 games with the Raiders. He also had 20 passes defensed, four fumble recoveries and two forced fumbles.
The Raiders also released linebacker Akbar Gbaja-Biamila, signed as a free agent earlier this offseason.
The Raiders began their second week of offseason practices Tuesday in a session closed to the media. It was the first time running back Darren McFadden and quarterback JaMarcus Russell got to work together.
McFadden, the No. 4 overall pick in last month's draft, was not allowed at last week's practices because he is a rookie. Russell, the No. 1 overall pick in 2007, was not at the rookie minicamp the previous week.