An Alberta man convicted of killing his wife will be given a new trial.

The North Carolina Court of Appeals overturned the guilty verdict against Medicine Hat native Bradley Graham Cooper Tuesday morning.

His wife Nancy’s body was found in a drainage ditch in 2008; she had been strangled and left not far from the family home outside of Raleigh.

Cooper called the police, telling investigators his wife had gone out for a jog and never returned.

Three years later, he was found guilty in what has since become the longest non-capital trial in the history of Wake County.

The couple had moved to the area in 2001 after being married in Calgary.

According to court documents, the Coopers’ relationship had become strained in the time leading up to Nancy’s murder.

The couple had an argument at a party the night before she went missing.

A Dateline documentary revealed the final straw in their relationship was an extramarital affair between Bradley and Nancy’s best friend.

Nancy filed for separation and attempted to take her daughters back to Canada, when her husband found their passports and hid them.

The key piece of evidence was a computer belonging to Bradley, where homicide detectives found a Google map on his hard drive.

It highlighted the subdivision and exact location as to where his wife had been found.

Police charged him with murder three months later.

Defence lawyers argued the map had been planted, his computer had been tampered with and they had witnesses ready to testify to that fact.

The presiding judge threw out their testimony, something two appellate court judges has since ruled “flawed.”

In the appeal, Cooper’s attorney argued the trial court’s ruling was an “abuse of discretion” and deprived their client of his right to mount a defence.

Wake County’s District Attorney Colon Willoughby Jr. tells 660News, he was surprised and disappointed by the decision.

“I thought the State had presented a good case and I thought the evidence of guilt was overwhelming and I thought if there were any errors, they were harmless errors and that the conviction should stand,” he says.

Willoughby believes Cooper was given a fair trial and this order is unwarranted.

It’s unclear how long this new trial will last; he says that partially depends on whether they seek a review by the U.S. Supreme Court.

“If not, then the case will come back for a new trial and that may take a period of months or even years depending on whether or not the same lawyers are appointed for him or whether he gets new lawyers,” he explains.

The District Attorney expects that decision will be made in the coming days.

Willoughby says the prosecutor who originally tried the case has been in touch with Nancy Cooper’s parents in Edmonton but declined to comment on their conversation.

“Periodically we have cases in which the Court of Appeals says the defendant is entitled to a new trial, that’s not an abnormality; that happens from time to time,” he says. “This one just happened to be a longer, more complex trial than usual.”