Greg Hall has been nominated by the Prince George's County Democratic Central Committee to replace former delegate Tiffany Alston. (Marvin Joseph/The Washington Post)

Maryland’s attorney general on Tuesday upheld a legal opinion that prevents former Prince George’s County legislator Tiffany Alston from returning to public office.

In a letter to Gov. Martin O’Malley (D), the state’s top lawyer confirmed that Alston’s House of Delegates seat became vacant at the time of her sentencing in a theft case last month.

Alston was found guilty of stealing $800 from the General Assembly last spring to pay an employee of her private law firm. But an Anne Arundel County judge this month modified her sentence to probation before judgment, essentially striking the finding of guilt.

The opinion became public just hours before the county’s Democratic Central Committee was preparing at O’Malley’s request to decide whether to withdraw the troubled nomination of businessman Greg Hall to succeed Alston. Committee members voted late Tuesday not to pull Hall’s nomination, putting his appointment back in the hands of the governor.

Alston, a first-term lawmaker, had asked O’Malley last week to stop the process of replacing her until the attorney general had reviewed the question of whether the modification of her sentence means she could be reinstated.

Tiffany Alston will not be allowed to return to public office in Maryland. (TIFFANY ALSTON)

Earlier this month, an attorney for the General Assembly advised House Speaker Michael E. Busch (D-Anne Arundel) that Alston was “permanently removed from elective office” after she received a suspended one-year jail sentence on Oct. 9. Nothing would prevent Alston from running again after her term expires in 2014.

The 12-page opinion signed by Attorney General Doug Gansler affirms the earlier finding that Alston gave up her right to appeal when she entered a plea agreement with state prosecutors in a separate case. Assistant attorney general Dan Friedman noted then that Alston’s agreement essentially prevented her from having her sentence “reversed” or “overturned,” which, he said, the Maryland Constitution requires for reinstatement.

The modification of Alston’s sentence to probation, according to the opinion on Tuesday, “does not amount to a determination that the conviction was wrongly imposed.”

With a second unfavorable opinion from the attorney general, Alston is likely to make good on her promise to file a lawsuit to try to get her old job back.

“I’ve tried to be diplomatic in working through these issues,” Alston said Tuesday. “But it’s apparent that the only just and equitable relief I’ll receive is from a court of law.”

In the meantime, Hall’s own troubled past — including a murder charge from 20 years ago that was dropped — has also given some local Democrats pause about his candidacy to represent the mid-county 24th District.

Prince George’s Sen. Joanne Benson, however, met with O’Malley last week to express her support for Hall, a former County Council aide who fell 310 votes short of winning the seat in 2010.

O’Malley has until Monday to act on Hall’s nomination. If the Central Committee had voted to pull Hall’s nomination Tuesday night, state law would have given the governor the power to appoint Alston’s successor without any local input.