By Suzi Parker

At a press conference Tuesday night in Fayetteville, Arkansas, Athletic Director Jeff Long said that Petrino, 51, was dismissed because of a "pattern of misleading and manipulative behavior to deceive me."

Petrino suffered four broken ribs and a cracked vertebra in his neck from a motorcycle accident on April 1. He appeared at a press conference on April 3 in a neck brace.

On April 5, Petrino was placed on paid administrative leave by Long after he failed to disclose that he had a female passenger, Jessica Dorrell, 25, on the motorcycle. Petrino hired Dorrell in late March as an assistant on the football staff.

Long said on Tuesday night that Petrino had given Dorrell $20,000. He did not disclose why the money was given to Dorrell, a former Arkansas women's volleyball player, or where the money came from.

Petrino violated university policy when he hired Dorrell, who was one of 159 applicants for the job, Long said. Petrino's relationship to Dorrell gave her "an unfair and undisclosed" advantage, Long said.

"I chose to engage in an improper relationship. I also made several poor decisions following the end of that relationship and in the aftermath of the accident. I accept full responsibility for what has happened," Petrino said in a statement.

Petrino apologized and said he would focus on repairing the damage to his family, including his wife, Becky, and four children.

Petrino left the Atlanta Falcons in mid-season in 2008 for the Arkansas coaching job. In 2010, Petrino took his team to its first Bowl Championship Series game. Arkansas finished with an 11-2 record in each of the last two seasons.

(Editing by Greg McCune and Eric Beech)