Harrick was fired by UCLA in 1996 -- a season after winning the national title -- for lying about an expense report.
Harrick then went to Rhode Island and took that school to the regional finals of the 1998 NCAA Tournament. He was accused of improprieties during his two years there.
A former secretary at Rhode Island said Harrick had grades changed for players, had student managers write papers for players and arranged for players to receive lodging, cars and money from boosters. In addition, Harrick Jr. was accused of falsifying hotel and meal reports for recruits when he worked for his father at Rhode Island.
Dooley and university president Michael Adams both read prepared statements Thursday night.
"This entire situation has been, and is, regrettable for the athletic program and the university,'' Dooley said.
"Coach Harrick is an accomplished coach of the game of basketball; however, I believe his resignation and retirement at this time to be in the best interests of the athletic association and the university, and coach Harrick obviously believes it is in his best interests, as well.''
Adams, who worked with Harrick at Pepperdine and was one of the greatest advocates of hiring him at Georgia, said he and Dooley had placed a lot of confidence in Harrick, "a man of considerable coaching talent.''
"We were greatly disappointed to lose that confidence due to coach Harrick's failure to appropriately manage the basketball program. Based upon the facts discovered in the investigation to date, his resignation is appropriate and we accept it,'' Adams said.
The investigation into the accusations made by Cole continue. Dooley and Adams emphasized their desire to complete that process, but they refused to speculate on any possible penalties from the NCAA.
"I do want to conclude that a lot of people have been hurt by this,'' said Dooley. "A lot of fans have been hurt, but especially the players. In so many ways my heart goes out to them.''
For the fourth time in a decade, Georgia is looking for a new head coach. Tubby Smith replaced Hugh Durham, who was dismissed after the 1995 season. Smith went to Kentucky after the 1997 season and was replaced by his assistant Ron Jirsa.
Jirsa lasted two seasons before he was fired, and replaced by Harrick.
Information from The Associated Press was used in this report.