Bangkok - Thailand's Supreme Court on Friday upheld a death sentence for a former deputy police commissioner for the murder of the wife and son of a gem trader allegedly involved in the theft of Saudi royal jewelry.

The court sentenced Police General Chalor Kerdthes to death 15 years after he allegedly arranged the murder of Darawadee Srithanakhan and her son on August 1, 1994.

Chalor was sentenced to death by the Appeals Court on March 3, 2006, but he appealed to the Supreme Court.

Chalor was convicted of killing the wife and son of Santi Srithanakhan while investigating the gem trader's involvement in the sale of jewelry stolen from the Saudi royal family in 1989 by Thai gardener Kriengkrai Techamong, a palace employee who stole millions of dollars worth of royal jewelry and smuggled it back to Thailand.

Santi was a prime suspect in selling the stolen items, including a blue diamond necklace that has never been recovered.

Chalor, after failing to track down Santi, was accused of abducting his wife and son, killing them and leaving their bodies in a parked Mercedes in the middle of a highway to be hit by a truck to make their deaths appear to be a car accident.

Chalor is alleged to be one of the few people in Thailand who knows where the stolen Saudi jewelry ended up.

The unsolved case has soured Thai-Saudi relations for the past two decades. Saudi Arabia has banned its tourists from visiting Thailand and ended all labour contracts with the South-East Asian country in the early 1990s.

The murders of three Saudi Arabian embassy officials in Bangkok has also been linked to the unsolved gems case.

Thai Prime Minister Abhisit Vejjajiva, when he took office in December, vowed to make the solving of the Saudi jewelry case one of his priorities. (dpa)