THE chief suspect in an unsolved 1999 Scottish murder faces extradition from Australia to stand trial.

James McGowan, 56, has been arrested in Adelaide more than 15 years after the fatal stabbing of his former brother-in-law Owen Brannigan in Coatbridge.

Mr McGowan, is now understood to have agreed to be handed over to UK authorities, according to reports in Australia.

The country's attorney-general's department, in a statement, said: "A dual citizen of Australia and the UK has been arrested pursuant to an extradition request for the UK for prosecution for murder and assault to severe injury."

The Scot, who has joint British and Australian citizenship, had been living in South Australia.

It is not known where he was in the country when he was arrested but he is understood to be in custody.

His former neighbours told local channel, Channel 7 News, that Mr McGowan had left his home some months ago. One man, who knew the Scot, told the TV station: "This is a shock to me."

Police Scotland have been seeking Mr McGowan since just a few days after 45-year-old Mr Brannigan died in a friend's house in Coatbridge, North Lanarkshire, on November 29, 1999.

A Scottish warrant was issued for Mr McGowan's arrest on December 3, 1999. However, Mr McGowan, who had been in Scotland to attend his mother's funeral, returned to Australia on the very day his warrant was issued.

He had told friends he intended to spend Christmas here and had brought presents for his family.

Detectives from the old Strathclyde Police force followed him to Adelaide but, as a naturalised Australian citizen, the Scot was able to refuse to co-operate with them.

The situation was described at the time as a catch-22 by police insiders as it meant that Scottish prosecutors did not feel there was enough evidence to seek extradition.

The victim Mr Brannigan, who was married to Mr McGowan's sister Carol until the 1980s, said they felt let down by the justice system.

Speaking in 2003, his other sister, Anne Marie, 43, added: "We just feel betrayed by the whole system of justice."

They family had contacted their local MP , who said he had been assured that any new evidence would be pursued.

That same year, Owen's brother, James, said "There are many aspects of this case we are unhappy with. It is deeply unsatisfactory."

Police at the time confirmed they were not looking for anyone else in connection with the killing.

The murder was one of the first to be looked at by the Crown Office's Cold Case Unit when it was set up in 2011.

It has been claimed that Mr McGowan, who is originally from Coatbridge, returned to Scotland to watch Hearts 2012 Scottish Cup victory over Edinburgh rivals Hibernian. It has also been reported that he has been back to Scotland on other occasions since the death.

The father of two lived until recently in a quiet Adelaide suburb of Salisbury Heights.

The current resident of his former home told a local TV news station that he receied a knock on the door of the property from pivate investigator some months ago, who was looking for Mr McGowan.

He said: "I had investigators on my doorstep. I told them that I had no idea where he is now."

Neighbours in the quiet Australian street were said to be shocked. "This is all a shock to me," said one a man who lives in the street. He added: "I would have had no idea that that sort of thing would have happened."