updated 9:35 a.m. ET March 21, 2007

HONOLULU - A former NFL player who joined the Marines and was motivated by college roommate Pat Tillman, who died in Afghanistan, was heading for the war in Iraq Tuesday night.

Lance Cpl. Jeremy Staat, a former defensive lineman for the Pittsburgh Steelers and St. Louis Rams who had been playing Arena Football, was one of 300 Marines in the 1st Battalion, 3rd Marine Regiment being deployed from Kaneohe Bay. The unit is expected to be in Iraq for seven months.

“The way I look at it, we’re spreading freedom, and you have to support the troops and you have to support the war,” Staat, 29, told KITV in Honolulu on Tuesday as he prepared to leave from Hawaii. “You can’t just tell some Marine who just lost his buddy that we supported you but not the war, because in that case you’re basically saying that Marine, his buddy, just died for nothing. We’re one team.”

Tillman, who played defensive back for the Arizona Cardinals, was killed by friendly fire near the Pakistan-Afghanistan border in April 2004. The Defense Department is investigating allegations of a coverup, including the Army’s failure to tell Tillman’s family for several weeks that he had been killed by gunfire from his fellow Army Rangers, not by enemy fire, as they initially were told.

Tillman gave up a $1.2 million NFL contract to join the Army Rangers.

Staat said he felt compelled to join the military after the Sept. 11, 2001, terrorist attacks, but Tillman, who was his roommate at Arizona State, advised him to stay with professional football until he qualified for retirement benefits.

Slide show   Week in Sports Pictures Flying on the hardwood, racing on the rink, getting physical on the gridiron, and much more. more photos

“I felt there is more to life than just a game,” Staat said, adding that Tillman’s death helped motivate him to enlist.

Staat played for the Steelers from 1998-2000, and played two games with the Rams in 2003. He was playing for the Los Angeles Avengers of the Arena Football League before being put on the league’s suspended list.

He graduated from the San Diego Marine Corps Recruit Depot in March 2006.

To enlist, the 6-foot-5 Staat said last year he dropped from 310 to 260 pounds. He said three months of boot camp training gave him a deeper appreciation for team camaraderie.

MORE FROM NFL

NFL Section Front

Brady vs. Manning — who has the edge? Cimini: Patriots-Colts greatest NFL rivalry of 2000s   Slideshow: Peyton vs. Brady through the years   Video: Playing 'what if?' with Peyton's career Report: Raiders want to fire coach Tom Cable Eagles-Bears matchup will remain Sunday night game PFT: Rest of league is catching up to Broncos PFT: Tomlinson hints at retiring after this season PFT: Ex-Packer Brown rips McCArthy PFT: Quinn reportedly will start for Browns again   NFL Section Front   Add NFL headlines to your news reader: