In Thursday's statement, Petrino admitted that he had kept quiet about Dorrell.
"My concern was to protect my family and a previous inappropriate relationship from becoming public," he said. "In hindsight, I showed a serious mistake in judgment when I chose not to be more specific about those details. Today, I've acknowledged this previous inappropriate relationship with my family and those within the athletic department administration."
He added: "I will fully cooperate with the university throughout this process and my hope is to repair my relationships with my family, my athletic director, the Razorback Nation and remain the head coach of the Razorbacks."
Dorrell, who did not return a call seeking comment, was hired March 28 by Petrino as the student-athlete development coordinator. She is in charge of organizing the recruiting process for the football team, including initial eligibility for each incoming player.
Long said he had not decided whether to suspend Dorrell but will make that determination after speaking with her in more detail. He said he spoke to her briefly on Thursday.
The police report said Petrino was riding with Dorrell when he lost control of his motorcycle. Dorrell said in the report that she wasn't sure what caused the accident, during which Petrino was unable to maneuver a turn and laid the motorcycle down on its left side while sliding off a rural, two-lane highway about 20 miles southeast of Fayetteville.
Petrino said in the report that wind and sun caused the accident. The police report said Petrino and Dorrell were taken by a passer-by from the scene of the accident to a shopping center in southeast Fayetteville, where a state police officer took Petrino to the hospital.
The police report said Dorrell wasn't taken to a hospital, and that she was dropped off at her vehicle at the shopping center.
State police spokesman Bill Sadler said Petrino didn't try to hide Dorrell's part in the accident when questioned on Tuesday.
"Coach Petrino was as cooperative as anybody that we could ever hope to encounter following the traffic crash," Sadler said. "He was very forthcoming with information when approached by the trooper who made the initial contact Tuesday afternoon."