Indiana Gov. Mike Pence angered many last month when he refused to pardon an innocent man, prompting questions of whether his status as vice presidential nominee for the Republican party affected his decision-making.

Keith Cooper was convicted of armed robbery in 1997 and sentenced to forty years in prison. DNA evidence exonerated him in 2006 and he was released, but legal complications left the stain of his felony conviction on record.

Mr. Cooper has been waiting for three years for a response to his plea for a pardon, but experts say a pardon based on innocence presents different challenges than other types of pardons.

Cooper says that Mr. Pence’s decision to deny his request for pardon by letter, particularly after pardoning three other individuals since he entered the governor’s mansion in 2013, is an affront.

“It’s just a slap in my face. It took him three years, three years to just write that letter,” Cooper said. “He could’ve done that three years ago.”

Cooper looked similar to a man who committed armed robbery and attempted murder at an apartment complex in Elkhart, Ind., in 1996, which contributed to his wrongful arrest and conviction. His attorney argued that flawed police work and unreliable witnesses, among other factors, also contributed to the conviction.

In 2006, DNA evidence proved that a hat found at the crime scene belonged, not to Cooper, but to another man who later committed a murder in Michigan, years after the robbery.

When the evidence was discovered, a judge gave Cooper two options: stay in jail while seeking a new trial to overturn the original conviction, or walk free with a felony conviction on his record. Cooper’s co-defendant, a man he has never met, chose the first option and later won a nearly $5 million civil rights suit against the state.

Cooper, the father to three young children, instead chose freedom in order to help his family, which he said was sometimes homeless while he was in prison.

Today, Cooper is only able to obtain low-wage jobs due to his criminal record, and says that while he does not regret choosing to help his family, he is now unable to earn a better living. He had hoped that obtaining Pence’s pardon would help him to better help his family.

Pence has granted three pardons in his tenure as governor to individuals who did not claim innocence. Previous Indiana Gov. Mitch Daniels issued 60 in eight years.

Legal experts say that pardons based on innocence are different than other pardons.

“A pardon based on innocence presents a very different set of circumstances to a governor. It requires the governor to determine that the trial court, and any appellate court which weighed the available evidence were wrong,” wrote general counsel Mark Ahearn, according to the Washington Post. “A pardon based on innocence requires a governor to substitute his judgment for that of the judicial branch.”

Pence’s press secretary says that neither race (Cooper is African-American) nor politics played any role in Pence’s decision to wait, or deny Cooper’s request.

Cooper says he had hoped Pence would be questioned about his decision to deny the pardon during the vice presidential debate.

"It crushed me a little bit," Cooper said of Pence’s decision. "I haven't give up hope. My hope is what keeps me strong, but I'm human and it hurts."