(CNN) Arizona Cardinal cum Afghanistan War hero Pat Tillman has been out of the public eye for some time, but his name popped up this week when his widow took President Donald Trump to task for politicizing her late husband.

Amid the debate about whether NFL players should kneel during "The Star-Spangled Banner," Trump on Sunday retweeted an image featuring Tillman wearing a tan Army Rangers beret alongside the hashtags, #StandForOurAnthem and #BoycottNFL.

In a statement Monday night , Marie Tillman said she hopes her husband inspires Americans to unite

"The very action of self expression and the freedom to speak from one's heart -- no matter those views -- is what Pat and so many other Americans have given their lives for," she wrote.

Here are five things to remember about Patrick Daniel Tillman:

He was small but fierce

Arizona State's Pat Tillman assists on a tackle during a November 1996 game against in-state rival Arizona.

After leading his San Jose, California, high school to a championship, he attended Arizona State University on a scholarship. At 5-foot-11, he was considered too small to play linebacker at a Division I school, but he proved his detractors wrong.

While racking up a bevy of awards for academics, his prowess on the gridiron also earned him accolades. He played four seasons, helping lead his undefeated Sun Devils to the Rose Bowl his junior year. After his senior season in 1997 -- during which he racked up 93 tackles, 15 of them for a loss -- he was named the Pac-10 Conference defensive player of the year, an award that now bears his name.

An Academic All-American, he graduated Summa Cum Laude, with a bachelor's degree in marketing, in 3½ years.

Cardinals took him with 226th pick

Arizona Cardinals safety Tillman smiles during pregame warm-ups in Tempe, Arizona, in 2000.

The seventh round of the NFL draft is not generally where teams find premier talent, but Tillman moved to the safety position and defied expectations again, playing in all 48 games for the Arizona Cardinals during his first three seasons, and starting in 27 of them. In 2000, he tallied more than 140 tackles along with a handful of turnovers and quarterback sacks.

After the 2001 season, which coincided with the September 11 attacks on the World Trade Center and Pentagon, Tillman turned down an offer from the Cardinals that would've paid him about $1.2 million year. He opted instead to join the Army for about $1,000 a month, according to reports at the time

He joined the Army with his brother

Tillman joined the Army just weeks after returning from his honeymoon with high school sweetheart Marie Tillman.

Tillman had two younger brothers, Kevin and Richard. Pat Tillman wasn't the only brother to forgo a career in pro sports to serve his country. Kevin gave up the prospect of a career with the Cleveland Indians, where he played second base in the team's minor league system.

After returning from his honeymoon in the spring of 2002, Pat Tillman told the Cardinals he would put his NFL career on hold to join Kevin. They enlisted together on May 31, 2002.

The brothers finished basic training together before completing the Ranger Indoctrination Program and joining the 2nd Battalion, 75th Ranger Regiment in Fort Lewis, Washington . They later took part in Operation Iraqi Freedom before returning to Fort Benning, Georgia, where they graduated from Ranger School.

After his brother was killed in Afghanistan, Kevin Tillman accompanied Pat Tillman's body back to the United States, according to reports.

Army didn't reveal friendly fire initially

Tillman, shown in this June 2003 photo, was killed in Afghanistan in 2004.

The initial claim was that Tillman died in an ambush outside the village of Sperah, near Afghanistan's border with Pakistan. He received a Silver Star and Purple Heart, and was posthumously promoted.

Twenty-six days after his memorial service, amid heavy criticism from Tillman's parents and brother Kevin, the Army publicly acknowledged that Tillman had died from friendly fire while returning to support members of his platoon from whom he and other Rangers had been separated. He died April 22, 2004 , after being shot in the head three times by US soldiers who had mistaken him for the enemy.

Later investigations and congressional inquiries included witnesses who said several soldiers and brass were immediately aware of the circumstances, and some sought to cover them up.

He left Marie a note

JUST WATCHED Marie Tillman on her late husband, Pat Replay More Videos ... MUST WATCH Marie Tillman on her late husband, Pat 00:59

Tillman's high school sweetheart and wife of two years, Marie, told CNN in 2012 that her husband left her a letter "just in case" he was killed while serving overseas. She opened it the night of his death.

"Through the years, I've asked a great deal of you. Therefore, it should surprise you little that I have another favor to ask. I ask that you live," she said, reciting Tillman's words.

Marie Tillman would go on to chronicle her life with and after Tillman. She called her book, "The Letter."