An Alexandria man whose conviction in a 2009 robbery was overturned last month will be tried again in a Fairfax County court on the same charge, according to a law firm.

A judge vacated the conviction of Maligie Conteh, 22, after finding prosecutors had unintentionally failed to disclose key evidence about the victim, who also was the only witness in the case.

Circuit Court Judge Randy L. Bellows said the fact that Alfredo Cordona-Lopez had been convicted of possessing a fake Social Security card cast doubt on his credibility as a witness.

In overturning the conviction, Bellows left open the possibility that prosecutors could pursue the case again.

A group that included the staff director of the Senate Finance Committee, the Innocence Project at the University of Virginia and lawyers at the firm of McGuire Woods also uncovered Facebook posts that they say prove Conteh could not have been at the scene at the time of the crime.

Conteh was convicted in 2010 of robbing Cordona-Lopez of $150, after the victim identified Conteh as the person who took his money behind the Plaza at Landmark shopping center in the Alexandria section of Fairfax County.

Conteh has always maintained he was at a friend’s house using Facebook around the time of the crime. The newly uncovered posts show a photo and message were posted to Conteh’s account about 11 minutes after the crime occurred.

Conteh served over a year in jail and was facing deportation to his native Sierra Leone, before his conviction was overturned. He had hoped to join the Marines and was expecting an acceptance letter the day he was arrested.

Anand Ramana, the attorney who filed the petition to have Conteh’s conviction vacated, said he was disappointed prosecutors would be putting Conteh on trial again.

“The two Facebook entries that Maligie posted within minutes of the alleged crime are indisputable evidence that corroborates Maligie's consistent alibi, and conclusively establish that Maligie is innocent," Ramana said.

Fairfax County prosecutors did not return a request for comment.