FAYETTEVILLE, Ark. (AP) — Arkansas athletic director Jeff Long says the affair that cost Bobby Petrino his job lasted for "a period of several months" before the coach recommended hiring his mistress.

The detail is disclosed in the letter that Long sent to Petrino on Tuesday to tell him he had been fired. The letter also says that Jessica Dorrell used a $20,000 "gift" from Petrino to buy a black Acura car during her first week on the job.

The letter was released Friday as part of a Freedom of Information Act request submitted by The Associated Press.

Long says Petrino deliberately failed to tell him he had "engaged in an extra-marital affair" with Dorrell before he told Long she should be hired last month. The university put the 25-year-old Dorrell on paid leave earlier Friday.