A spokesman for the Steelers confirmed the news but didn't disclose a cause of death.
Haggans spent his first eight years in the NFL in Pittsburgh. He appeared in 107 games, recording 332 tackles and 32.5 sacks. A fifth-round pick in the 2000 draft, he started as a backup for the Steelers before emerging as a key piece of the defense.
One of Haggans' best individual years coincided with Pittsburgh's return to the NFL summit. He collected nine sacks and forced four fumbles in 2005, a campaign that ended with the team celebrating its fifth Super Bowl title.
Haggans signed with the Arizona Cardinals ahead of the 2008 season and was a member of the team through 2011. He finished out his career with the San Francisco 49ers in 2012 and made nine appearances as the Niners captured the NFC title.
