A black man who was found not guilty of armed robbery will still serve up to seven years behind bars after a judge ruled he had breached the rules of his probation sentence for another crime.

Ramad Chatman handed himself in to police when he found out he was a suspect for an armed robbery at a convenience store in his hometown of Georgia in July 2014.

"He turned himself in because he knew he was not guilty," his grandmother Janice Chatman told US news channel 11Alive.

The 24-year-old was already was serving a five year probation term (a court order served outside prison through fines and community service) for his first ever offence, breaking and entering an apartment to steal a television worth $120 (£92) in 2012.

He was identified as a suspect for the armed robbery in the winter of 2014 after the shop assistant spotted his picture on Facebook. She identified him again when police showed her his driving licence picture.

Quite why it took police so long to catch up with Chatman is unclear, but after hearing officers were looking for him, he turned himself in in November 2015.

The following February, a judge decided it was likely he did commit the robbery and as a result Chatman was re-sentenced for the original crime of stealing a TV and ordered to serve 10-years behind bars, back dated to the day of the crime.

Court documents nonetheless showed he did everything asked of him during his probation, including checking in, paying restitution and finishing his community service. He was also holding down a job.

But when the armed robbery trial came to court in August, he was found not guilty.

It later emerged that ahead of the trial Chapman tried to enter an Alford plea on the charge of aggravated assault in exchange for the armed robbery charges being dropped.

An Alford plea means the defendant enters a guilty plea, but maintains his innocence. It is often used when a defendant feels like despite his innocence, he will lose at trial.

The judge refused to accept the deal, so the case was heard before a jury - who ruled he was innocent of the crime.

Presiding Judge John Niedrach, disagreed with their verdict however.

So despite the fact police never recovered the weapon, stolen money, or any other evidence connecting him to the robbery, he declined to release Mr Chatman, who remains in prison for violating the terms of his first probation order.

Mr Chatman’s grandmother told 11 Alive he had worked hard to meet the terms of his court order, including paying his mandated fines on time.

“He made sure he did right on his probation. He never violated it.”

“What Judge Niedrach has done to my grandson is an injustice,” she told the Rome News Tribune. “When my grandson was proven not guilty, he should’ve been let out.”

In 2016, 38 percent of US prison inmates were black, despite only comprising 13 per cent of the general population, according to the Federal Bureau of Prisons.