Yesterday, O'Brien, 32, would only confirm that he had tendered his resignation to Georgia Tech, where he began working as graduate assistant coach in 1995.
He became the Yellow Jackets' running backs coach in 1998 and rose to their top offensive post after the 2000 season, when Ralph Friedgen left to become Maryland's head coach.
Despite overtures from NFL teams for assistant jobs, he stayed on as Tech's offensive coordinator after former Miami Dolphins offensive coordinator Chan Gailey replaced George O'Leary as head coach last year. But Gailey had publicly stated he would be taking a more active role in the Yellow Jackets' offense.
Sharpless, a coaching veteran of 26 years and the Terps' inside linebackers coach for the past two seasons, resigned last weekend after allegedly giving $300 to a potential recruit, Gilman's Victor Abiamiri, sparking an internal review of the school's recruiting practices.
The review, which began last week, is expected to take another week before its findings are sent to the NCAA.
It is still unclear whether O'Brien will perform Sharpless' old duties, or whether Friedgen will create another position. O'Brien would be the third assistant to follow Friedgen from Georgia Tech to College Park - defensive line coach Dave Sollazzo and assistant recruiting coordinator John Donovan made the move in 2000.