The body of a former Haworth man and his wife are to be exhumed in South Africa in a bid to solve a murder mystery.

Police now suspect that Robert Green, 65, poisoned his wife, Joy, and then poisoned himself before setting fire to their home in Johannesburg.

Detectives at first thought the 65-year-old couple were victims of a double murder.

Two Mozambique-born brothers, Moses and Johan Mamba, were arrested and are still held in custody.

But Mr Green's brother, Jack Green, of Wardle Crescent, Keighley, said he had now been told by his brother-in-law in South Africa that the brothers were unlikely to be prosecuted.

Clothes found in their possession, which were at first thought to have been Robert Green's, were later found to be too small for the Yorkshireman.

Signs of a break-in were found to have been caused by firefighters trying to get into the house after the alarm was raised.

The post mortem examination revealed that Mrs Green died before the fire began but her husband had not.

Detectives are now to exhume the bodies so new blood samples can be taken. Jack Green, a 57 year-old bricklayer, said: "My wife and I have talked and talked about it but cannot understand it. Bob was always a churchgoer. It's completely out of character."

He accepted that his brother could have been involved.

"Whatever he administered must have been very powerful because his wife was in a very relaxed position in bed when she was found. It seems he moved to another part of the house and set a fire and then did himself in -- that's what the police think."

His wife, Linda said: "There are two alternatives -- either those two men did kill them or Robert took his own life and his wife's."

But the reason still remained a mystery and detectives were investigating why Robert -- who emigrated about 40 years ago -- had been withdrawing large amounts of money from his account.

Mr Green added: "Between August 2000 and April this year, when the tragedy happened, he had been regularly withdrawing between 300 and 600 rand. Nobody knows why. Was he being blackmailed or was drugs involved -- I doubt that.

"Nobody knows where he spent it or what he spent it on," said Mr Green.

Robert Green was brought up in Haworth and worked as an apprentice blacksmith in Keighley before doing national service in Cyprus and later emigrating.

The couple had one son, Christopher, who died of muscular dystrophy more than 15 years ago.

There was nobody available at the British consulate in Johannesburg to comment on the latest developments.