Sources close to Matua said the cause of death was heart related. Matua had been hospitalized recently, and former teammates had taken to social media to ask for support and prayers.
The 6-foot-2, 305-pound Matua was a three-year starting offensive guard for the Trojans from 2003-05. He was part of the team's 34-game win streak, the 2005 Notre Dame "Bush Push" game and the BCS title game victory against Oklahoma, which has since been vacated.
Matua played at Banning High School in Wilmington, Calif., where he led the Pilots to the 2000 Los Angeles City title and earned All-American honors as a two-way lineman. He chose USC in a recruiting battle over UCLA -- his uncle, Titus Tuiasosopo, had played offensive guard for the Trojans in the 1990s.
When Matua first arrived at USC as a freshman there was debate over where he would play. He was a spirited and intense competitor with a defensive lineman's mentality -- which would have fit well with defensive coordinator Ed Orgeron -- but the USC coaches wanted to bring that kind of attitude to the offensive line, so Matua began his career there.
USC Hall of Fame writer Loel Schrader commented at the time, "Fred doesn't care which side of the ball they put him on, he's just gonna kick the ass of the guy across from him."
Matua had no problem acknowledging his fiery nature.
"I can't change," Matua said during an interview. "Same volume every day -- loud. You've got to be loud. It's a street attitude. The way I act is in a defensive manner. Defense was my identity when I came here, that's just me."
As a true freshman, Matua was in line to start the 2002 season opener against Auburn but hurt his knee in fall camp. He saw limited action early in the season before having surgery and taking a redshirt year.
By the time the 2003 season rolled around the Trojans were ready to unleash an offensive arsenal on the college football world, and Matua helped form the core of an offensive line that also featured future All-Americans Ryan Kalil and Sam Baker. In 2004, Matua was named a sophomore All-American, and in 2005, he was named Second Team All-Pac-10.
Matua left USC after his junior year and was selected in the seventh round of the 2006 NFL draft by the Detroit Lions. Between 2006-08, he spent time with the Lions, Tennessee Titans, Cleveland Browns and Washington Redskins. He also played in the United Football League in 2010.
Several former USC teammates expressed their condolences on Twitter after hearing that Matua passed away Sunday morning:
• Keith Rivers @rivers55: "Really heavy heart right now."
• Brandon Hancock @BrandonJHancock: "Very saddened this morning. Former teammate Fred Matua passed away from hrt failure. U will be missed my SC Brother. Thoughts to ur fam RIP"
• LenDale White: @THEREAL_LENDALE: "Sad day for the Trojan family. Say a prayer for the Matua family thank u"
• Deuce Lutui @DeuceLutui: "To my beloved brother FRED MATUA the guy who is a big credit to my career he sacrificed himself to lift me I love U. USCDYNASYTrojans4Life"
• Keary Colbert @kearycolbert: "I just lost a former teammate/brother, Fred Matua. Heavy Hearts for the Trojan Family"