TEMPE, Ariz. -- Tyrann Mathieu could barely get the words out, the sobs and tears muffling his voice through the telephone.

"I know I'm on the right track," he said.

The Arizona Cardinals seem to think so.

After relatively safe choices in the first two rounds of the NFL draft, the Cardinals took a chance in the third by taking Mathieu, the talented-but-troubled cornerback out of LSU.

Based on their own evaluations and the word of their Pro Bowl cornerback Patrick Peterson, Mathieu's former LSU teammate and one of his closest friends, the Cardinals used the 69th overall pick Friday night to take the player affectionately known as the Honey Badger.

"He impressed me so much in my office one on one, knowing at this point in time what he needs to do in his life," Cardinals first-year coach Bruce Arians said. "I was really taken aback a little bit. He knows what his problems are, he knows what he has done to himself, but he also knows that someone will give him a chance, that he knows what he needs to make sure he succeeds."

Once considered a Heisman Trophy front-runner and sure-bet first-rounder, Mathieu became a risky choice for NFL teams after a string of off-the-field incidents put his character in question.

A Heisman Trophy finalist in 2011, Mathieu was kicked off the team by LSU coach Les Miles in preseason camp last August for failing multiple drug tests.

Mathieu, who didn't play in 2012, was arrested less than two months later with three former teammates after police found 10 bags of marijuana and drug paraphernalia in his Baton Rouge apartment.

Mathieu spent two weeks in a drug treatment program run by former NBA player John Lucas and the months leading up the draft trying to rehabilitate his image. He spent some of that time with Peterson, who vouched for his friend to the Cardinals front office and coaching staff before they picked him in the draft.

"The guy is ready to play football," said Peterson, who said he will continue to mentor Mathieu with the Cardinals. "He made a mistake, was in an unstable position where he got caught with the marijuana, but he understands the importance of being accountable and being a role model, so that stuff is behind him."

Before his fall from grace, Mathieu was one of the nation's most dynamic players, a game-changing force who was a threat to score every time he touched the football, whether on kick returns or turnovers.

Mathieu finished fifth in the Heisman Trophy voting in 2011 and was the first defensive back to be invited to the ceremony in New York since Michigan's Charles Woodson won the award in 1997. He also won the Bednarik Award as national defensive player of the year, was an All-American and forced 11 career fumbles, seventh-most in NCAA history and a school record.

Once the troubles hit, Mathieu's stock plummeted, causing teams to bypass him in the draft.

Mathieu worked on fixing his image with Peterson and said he would be willing to undergo weekly drug testing, see drug counselors, therapists -- whatever the Cardinals want.

He's thrilled to have a second chance and plans to make the most of it.

"Their biggest thing is that they want to know that they can trust me," Mathieu said. "They want to be able to know that I've crossed that bridge."

The Cardinals were convinced Mathieu was serious about changing his life after thoroughly researching his background.

They flew Mathieu out to Phoenix, had dinner with him, spent time with him and Peterson together, and traveled to LSU's campus to speak with just about every staff member who came in contact with him on campus.

The Cardinals also had conversations with Peterson about Mathieu's background and character, and plan to have wording in his contract to keep him on the right track.