In a year when the Atlanta Falcons secondary figures to undergo a major overhaul, the team maintained some stability on Thursday, reaching a contract agreement to retain unrestricted free agent Keion Carpenter.

The four-year veteran was the team's starting free safety in 2002, tested the free agency market over the past six weeks, but opted to return to Atlanta. The move is a significant one for Atlanta, given that Carpenter is coming off a very good season, and makes most of the secondary coverage calls.

Atlanta also completed a trade, sending three-year veteran offensive tackle Michael Thompson to the Seattle Seahawks, and netting a low-round draft choice in return. The active Falcons added two unrestricted free agents as well, reaching accords with offensive lineman Kevin Dogins and placement specialist John Markham.

But the biggest transaction was keeping Carpenter, who had drawn modest interest as an unrestricted free agent, who had been in relatively substantive talks with the Houston Texans just two weeks ago.

Contract details were not yet available for Carpenter, but it is believed that he will sign a one-year deal, as he did in 2002.

Carpenter, 25, came to the Falcons following three seasons in Buffalo, after the Bills did not tender him a qualifying offer last spring. He led all Atlanta secondary players with 73 tackles and also had four interceptions to go with 10 passes defensed.

The advantage Carpenter had when he joined the Falcons was a familiarity with the scheme being installed by first-year coordinator Wade Phillips, his head coaching for two of three seasons with the Bills.

Atlanta has signed two free agents, strong safety Cory Hall and cornerback Tyrone Williams, as new starters in the secondary for 2003. There had been some talk the Falcons would move cornerback Ray Buchanan to free safety, but that is not a likely switch now, given that Carpenter will return.

A former Virginia Tech star, Carpenter has 140 tackles in his career and nine interceptions. He has played in 43 games and started 38.

The trade of Thompson was not unexpected. Atlanta had agreed to trade the three-year veteran to Miami last week, but the deal was negated when he did not pass the Dolphins physical examination because of perceived problems with his knees. Thompson immediately flew to Seattle, where he passed the Seahawks exam over the weekend, and the two teams quickly struck a deal.

Actually, the Seahawks had inquired about Thompson last month, so Atlanta officials were aware of their interest. Thompson probably will be the No. 3 tackle in Seattle, behind starters Walter Jones and Chris Terry. But he also provides the Seahawks a nice insurance policy in the event that Jones, who is designated a "franchise" player, misses the start of training camp.

A former Tennessee State standout, Thompson has been limited, because of circumstance and injury, to 12 appearances and four starts. But scouts feel he possesses excellent athletic tools and, at age 26, he still has enough time to develop into a starting-caliber player. Thompson was a fourth-round pick in the 2000 draft.

Dogins is a seven-year veteran who can play guard and center. He adds depth to the Falcons interior offensive line after five seasons in Tampa Bay and the last two years with the Chicago Bears. Markham was selected by the New York Giants in the fifth round of the 2001 draft, released in camp, and was not in the league in 2002.

Len Pasquarelli is a senior writer for ESPN.com.