FAYETTEVILLE, Ark. -- Arkansas fired head coach Bobby Petrino on Tuesday, publicly dressing him down for unfairly hiring his mistress and intentionally misleading his boss about everything from their relationship to her presence at the motorcycle accident that ultimately cost him his job.

Athletic director Jeff Long announced his decision at an evening news conference and laid out a stunning laundry list of misdeeds by the man he hired away from the Atlanta Falcons four years ago.

They included ignoring multiple chances over the past 10 days to come clean to Long about a relationship that had crossed the line from infidelity into workplace favoritism.

"He made the decision, a conscious decision, to mislead the public on Tuesday, and in doing so negatively and adversely affected the reputation of the University of Arkansas and our football program," Long said, choking up at one point as he discussed telling players that their coach was gone. "In short, coach Petrino engaged in a pattern of misleading and manipulative behavior designed to deceive me and members of the athletic staff, both before and after the motorcycle accident."

Long said Petrino was fired "with cause" -- meaning he will not receive the $18 million buyout his contract called for -- and there were no discussions about ways to keep Petrino at Arkansas.

The 51-year-old Petrino, a married father of four, had maintained an inappropriate relationship with 25-year-old Jessica Dorrell for a "significant" amount of time and at one point had given her $20,000, Long said.

He would not disclose details of the payment, or when the money changed hands, but said both parties confirmed the "gift." Kevin Trainor, a spokesman for Long, said the money came from Petrino, not university funds.

Petrino, who was fired via a letter from Long, issued a lengthy apology and said he was focused on trying to heal his family.

"The simplest response I have is: I'm sorry. These two words seem very inadequate. But that is my heart," Petrino said in a statement. "All I have been able to think about is the number of people I've let down by making selfish decisions. I've taken a lot of criticism in the past. Some deserved, some not deserved. This time, I have no one to blame but myself.

"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."

Dorrell, a former Razorbacks volleyball player, worked for the Razorbacks Foundation before she was hired by Petrino on March 28, four days before their accident on a winding rural road. Long said she was one of three finalists out of 159 applicants and got the job after a time frame he said was shorter than usual.

Petrino never disclosed his conflict of interest in hiring Dorrell or the payment, Long said.