FAYETTEVILLE, Ark. - Arkansas put the former mistress of Bobby Petrino on paid leave Friday and disclosed that she used a $20,000 "gift" from the disgraced former coach to buy a car in her first week on the job.

University spokesman Steve Voorhies said Jessica Dorrell, a 25-year-old football department employee, had been placed on leave but declined further comment, calling it a private personnel issue.

Dorrell, a former Arkansas volleyball player, was a Razorback Foundation fundraiser before she was hired as a student-athlete development coordinator by Petrino on March 28 at an annual salary of $55,735. She has not returned repeated calls seeking comment.

The move came as Petrino said he would not appeal his firing and seek any of the $18 million buyout that was part of his contract. His agent, Russ Campbell, sent an email to athletic director Jeff Long late Thursday saying Petrino had accepted "responsibility for the events that led to the university's decision to terminate his contract."

"Coach Petrino and his family wish nothing but the best for both the Razorback football program and University of Arkansas," Campbell wrote.

Petrino had the option to appeal as part of the seven-year contract he agreed to in December 2010. The contract was for more than $3.5 million annually and carried the $18 million mutual buyout clause in 2011 and 2012. The amount dropped over the life of the contract, falling to as little as $3.9 million in 2017.

Long said that Petrino was fired for cause, meaning the coach was not owed anything.

The 51-year-old Petrino was fired Tuesday for failing to disclose his relationship with Dorrell before she was hired, as required by conflict of interest rules at the school. The affair became public only after the two went for a motorcycle ride April 1 and skidded off the road, putting Petrino in the hospital and resulting in a police report that contained her identity.

Long has said the two were in a relationship for a "significant" amount of time and phone records show they exchanged more than 4,300 text messages and nearly 300 phone calls over the past seven months, possibly including photo and video content.

The termination letter Long sent to Petrino was released by the school Friday and it had more specifics.

"(Y)ou deliberately failed to tell me that you had engaged in an extramarital affair with Ms. Dorrell over a period of several months leading up to your recommendation to hire her," Long wrote. "If you had been forthcoming with me about the true nature of your relationship, I would not have approved the hiring."

Long also said Petrino "admitting giving $20,000 cash to Ms. Dorrell as a 'gift.' Ms. Dorrell used the money to purchase a black Acura during the first week that she worked for the football program.

"Among other concerns relating to this 'gift,' you should have disclosed this fact to me ... but you failed to do so," Long wrote.

The athletic director ripped Petrino for "poor judgment" and said that by lying to his boss and the public he had left the school with the task of "restoring the reputation of our institution and our athletics programs."

"I recognize that you are a very talented football coach," Long wrote, "but the university may not disregard your conduct or sacrifice its integrity, reputation and principles."

As for Dorrell, it is unknown whether she will face the same fate.

In a March 20 letter Long sent to Dorrell offering her the job, he wrote that "you should be aware that you will be held accountable for and must abide by University of Arkansas, Southeastern Conference and NCAA rules and regulations."

The school, he added, "expects integrity" and Dorrell was asked to comply with "conflict of interest policies" among other things. The letter amounts to an "understanding" that there are "no agreements, whether written or oral, regarding your employment other than those contained in this letter." The letter was signed by Dorrell.

A person familiar with the situation has told the AP that Dorrell had "at one time" been engaged to another athletic department staffer, assistant strength and conditioning coach Josh Morgan. Voorhies said Morgan is still employed by Arkansas.