With the re-signing of inside linebacker London Fletcher and defensive end Adam Carriker this spring, the Washington Redskins ensured that in 2012 they would keep intact the front seven of a unit that greatly improved last year.

After ranking 31st in the NFL in total defense in 2010, their first season in a 3-4 scheme, the Redskins improved to 13th in the league last season despite an inconsistent and injury-plagued secondary.

The team returns 2011 first-round draft choice Ryan Kerrigan, who complements star outside linebacker Brian Orakpo, as well as nose tackle Barry Cofield and end Stephen Bowen — all of whom teamed with Carriker to give Washington a formidable line last season. The Redskins also re-signed veteran defensive end Kedric Golston and get back 2011 second-round pick Jarvis Jenkins, who has recovered from the ACL tear he suffered last preseason.

“We think the front is about as good as it gets,” defensive coordinator Jim Haslett said earlier this offseason. “But we need to get some stability on the back end. . . . We’re not done rebuilding and we’re not done doing the things we want to do on defense.”

So despite more pressing needs on offense, the Redskins likely will look to make a draft selection or two to improve depth and add competition on defense. Safety represents one of the biggest needs.

This offseason, the team allowed dynamic — yet oft-injured — strong safety LaRon Landry to depart via free agency. A bad Achilles’ tendon had limited Landry to a combined 17 games in the last two seasons, and he elected not to have surgery during the offseason.

The Redskins were leery of making a significant investment in a player who ended the last two seasons on injured reserve.

The team also released free safety Oshiomogho Atogwe in March. Atogwe battled various injuries and didn’t perform as well as the team had hoped.

Six-year veteran Reed Doughty and then-rookie DeJon Gomes saw significant playing time last season. The hope is that Gomes — one of the Redskins’ fifth-round picks last April — can develop into a starter in his second season. But Washington also signed veteran free agents Brandon Meriweather, Tanard Jackson and Madieu Williams during the offseason. None of those players was a full-time starter last season, however.

The team, according to a person with knowledge of the situation, has had contact with Syracuse safety Phillip Thomas, a projected mid-round player. Thomas last season intercepted six passes, which ranked sixth nationally.

Other safeties expected to be available in the third through fifth rounds include Antonio Allen of South Carolina, Michigan State’s Trenton Robinson, Aaron Henry of Wisconsin and Janzen Jackson of McNeese State.

At cornerback, DeAngelo Hall and Josh Wilson return as starters, but Washington lacked a consistent option at nickelback. Kevin Barnes, who split time at that spot with Byron Westbrook, remains under contract, but Westbrook is a free agent. Brandyn Thompson — one of Washington’s seventh-round picks in 2011 — remains on the roster after appearing in six games during his rookies season. The Redskins also added veterans Leigh Torrence and Cedric Griffin in free agency.

Talented corners are likely to be available for the Redskins, who have a third-round pick, two fourth-rounders, a fifth, a sixth and a seventh. But the question for a team that also has needs at other positions is how long can they afford to wait before taking one.

“The cornerbacks are going to come flying off the board,” ESPN draft analyst Mel Kiper Jr. said. “. . . I roughly see 25 to 27 cornerbacks that could be in the top 150, 175. In this league, this pass happy league, you’ve got to have corners.”

One third- or fourth-round option could be Arizona State’s Omar Bolden. He established himself as one of college football’s top corners in 2010 after he earned all-Pacific-12 Conference first-team honors. He missed last season with a torn ACL.

Bolden, fully recovered, clocked a 4.51-second 40-yard dash at his school’s pro day last month and possesses the talent of a higher-round pick. But because of his injury history, he isn’t expected to hear his name called until the middle of the draft.

Oklahoma’s Jamell Fleming, Furman’s Ryan Steed, West Virginia’s Keith Tandy, Iowa State’s Leonard Johnson and Texas A&M’s Coryell Judie also lead a group of cornerbacks projected for selection in the middle rounds.

Though it is a less pressing need, the Redskins may want to look at inside linebackers. Fletcher and third-year pro Perry Riley are the starters, and Lorenzo Alexander and free agent addition Bryan Kehl are expected to serve as the backups.

Mid- to late-round prospects include Nevada’s James-Michael Johnson, Kyle Wilber of Wake Forest, Arizona State’s Vontaze Burfict and Audie Cole of N.C. State.