The Redskins placed safety Reed Doughty on injured reserve and signed defensive back Mike Green to the roster, the team announced on Tuesday.
Green is a 9-year veteran who has played with the Chicago Bears and Seattle Seahawks.
Doughty has been sidelined with a back injury.
The 6-1, 209-pound third-year player out of Northern Colorado started two of the Redskins' first six games--versus the New York Giants and Arizona Cardinals.
He was inactive for the Redskins' 19-17, Week 6 setback to the St. Louis Rams at FedExField.
Rookie Chris Horton has assumed the bulk of the work at strong safety, alongside free safety LaRon Landry.
Doughty had six total tackles in the opener at the Meadowlands and eight total tackles against the Cardinals.
He was a starter six times in 2007, producing 51 tackles and a half sack.
Green played in Chicago under current Redskins defensive coordinator Greg Bache.
He spent the first six years of his career with the Chicago Bears and started 45 of 81 games for the Bears.
Traded to Seattle during the 2006 offseason, Green missed his first year with the Seahawks after being placed on injured reserve with a Lisfranc injury.
He played in 15 games for Seattle last year, including one start, and logged 17 tackles and one pass defended.
For his career, Green has 406 tackles (327 solo), six sacks, seven forced fumbles and four interceptions.
The Ruston, La., native, Green attended Northwestern State.