Photo: Dec. 2011 ICON Sports Media Ravens Jarret Johnson (95) tackles Chargers running back Ryan Mathews #24 during the NFL regular season game between the Baltimore Ravens and the San Diego Chargers at Qualcomm Stadium in San Diego, CA.

The Chargers have signed 12 total unrestricted free agents this offseason, 10 of which have signed since the free agency signing period began March 13th.

Dante Rosario, tight end

The 6-4, 250 pound Rosario was a fifth-round pick by Carolina in 2007. He played four seasons (2007-10) for the Panthers and played in Denver in 2011. Rosario has 89 catches for 1,011 yards and five touchdowns during his career. He played in 14 games for the Broncos last season and has played in 78 during his career, starting 25. He is 27 years old.

Last season with Denver he caught seven passes for 117 yards.

Rosario will compete to be the Chargers No. 3 tight end with Kory Sperry, behind starter Antonio Gates and Randy McMichael.

Other notables: Rosario's mother died of cancer in December of 2001 after a 10-year battle. His father Pedro, pitched in the Atlanta Braves organization.

Atari Bigby, strong safety

Bigby, now entering his seventh official NFL season, has played in 61 NFL games, starting 27 for Green Bay in 2007-09. The 30-year-old safety made his professional debut on Christmas in 2005 after bouncing between three teams as an undrafted rookie. He spent most of 2005-06 on Green Bay’s practice squad before becoming a starter for the Packers in 2007.

Other Notables: Bigby was born in Jamaica but moved to the U.S. at the age of four. Named Atari by his grandmother, who liked the name. “Atari” is Japanese for a form of the word “attack”.

Jared Gaither, left tackle

Claimed off waivers Nov. 30 from the Kansas City Chiefs, Gaither started the final five games of the 2011 season for the Chargers and did not allow a sack during the 4-1 finish.

Gaither signed a four-year contract with the Chargers on March 12. He should be the Chargers' starting left tackle Week 1.

Jarret Johnson, outside linebacker

Johnson had 56 tackles and 2.5 sacks for the Ravens in 2011, playing under then defensive coordinator Chuck Pagano who is the brother of Chargers defensive coordinator John Pagano.

The 6-foot-3, 260-pound linebacker played the first nine seasons of his career in Baltimore. He played in a Ravens’ franchise-record 129 consecutive regular-season games and has started 89 in a row, including playoffs. Baltimore selected him in the fourth round (109th overall) of the 2003 NFL Draft out of Alabama.

"Everyone talks about how he plays great run defense,” Chargers defensive coordinator John Pagano told the San Diego Union Tribune. “But the big missing component for people is he can rush the passer. He can put pressure on that edge. I think he’s somebody that’s going to have, let’s just say more of an opportunity to do those types of things … To just label him as a run stopper, no. I think his overall game as an outside linebacker is a real positive for us."

Johnson told the Chargers official website, "You wouldn’t call me a pass-rush guru. I’m a capable pass rusher, but I think my versatility is my strength. I played Sam linebacker for Baltimore and Sam has to do a lot of jobs. Lots of dropping in coverage, different types of coverages, rushing from different sides, line up pretty much at every position. That’s why I’m excited about playing for John is he has a similar defense and I’m going to be able to line up in different spots and be able to be another weapon that he’s already got with Shaun Phillips and all the other guys they already have on that defense. I just want to be there to add another weapon."

Other notables: He is the Alabama Crimson Tide's third all-time career sack leader with 23.

Le’Ron McClain, fullback

McClain was added to replace fullback Jacob Hester as Ryan Matthews' lead blocker.

The 6-foot, 260-pound back is a physical runner who has split time between running back and fullback. He rushed for 902 yards on 232 carries for Baltimore in 2008, though he spent more time as a lead blocker from 2009-11 and is expected to play fullback for the Chargers. McClain played for Kansas City last season and averaged 18.8 catches per season over the last four years.

Other notables: Besides starring at the University of Alabama, is also most known for allegedly spitting in the face of Dolphins linebacker Channing Crowder in 2010.

Robert Meachem, wide receiver

Meachem, 6-2, 210, was chosen by the Saints in the first round of the 2007 NFL Draft and has been a key contributor to one of the most productive offenses in the NFL. In 2011, the 27-year-old Meachem averaged 15.5 yards on 40 receptions for 620 yards and six touchdowns. He has caught 23 touchdowns passes and averaged 16.1 yards per catch in five NFL seasons.
Other notables: The Tulsa, OK native has deep roots in rodeo, learning the sport from his father.

Eddie Royal, wide receiver/punt returner

The fifth-year receiver caught 91 passes for 980 yards as a rookie in ’08 with the Denver Broncos and has averaged 38 catches for 376 yards since. In 2011 with Denver he caught 19 passes for 155 yards and one touchdown.

He will compete as the third or fourth receiver on the Chargers depth chart and will have an opportunity as a punt returner.

Royal agreed to a three-year, $13.5 million contract, with $6 million guaranteed.

Randy McMichael, tight end

The 32-year old will play his 11th NFL season in 2012, the last two coming with the Chargers. In 2011 he played in 16 games, 14 as a starter. He caught 30 balls for 271 yards.

McMichael signed a 2-year $2.7 million contract. McMichael also has proved valuable as a special teams player, making six tackles in 2011.

McMichael is generally regarded as a throwback football player, one who loves to mix it up and play regardless of his position or role.

Kory Sperry, tight end

The Chargers signed Sperry back as a special teams player and the team's No. 3 tight end behind Antonio Gates and McMicheal.

In 2011, he played in all 16 games, starting 4, catching one pass for 14 yards. . Originally signed by the Chargers as an undrafted rookie from Colorado State in 2009. After being waived, he re-signed with the Chargers to the practice squad in September of 2010, making the active roster in November of that season.

Other notables: His full name is Kory Kalani Kahaunaele Sperry...held first job as promoter for Crunk energy drink

Charlie Whitehurst, quarterback

Whitehurst toiled as the backup to Tarvaris Jackson and even started two games, but generally was ineffective in moving the ball. But with the release of Billy Volek, Whitehurst is Philip Rivers' backup and one who has NFL game experience and a great familiarity with the Chargers. Whitehurst was drafted by the Chargers in the third-round of the 2006 Draft.

Nick Hardwick, center

Hardwick signed a three-year contract before the free-agency period began, reportedly worth $13.5 million. Hardwick started all 16 games for the Chargers in 2011. Hardwick has started 103 games for the Bolts since 2003.

Demorrio Williams, linebacker

Williams played in 12 games without a start for the Kansas City Chiefs in 2011. Williams, 32, signed a one-year contract with the Chargers.