ALAMEDA, Calif. (AP) - The Oakland Raiders have signed former Atlanta defensive tackle Vance Walker to a free-agent contract.

The team announced its latest move to upgrade a depleted defense on Monday.

Walker is the sixth defensive free agent signed by Oakland in the past week. He joins tackle Pat Sims and Jason Hunter on the line with linebackers Nick Roach, Kaluka Maiava and Kevin Burnett also added to the mix.

The Raiders are also talking to cornerback Terrence Newman. Newman says he expects to make a decision about whether to remain with Cincinnati or sign with Oakland sometime this week.

The Raiders are expected to bring back only three starters from the defense that gave up the fifth most points in the NFL last season.