By Steve Kingstone BBC correspondent in Washington

The United States military is investigating a disturbing series of murders apparently involving US special forces soldiers who recently served in Afghanistan.

Andrea Lloyd is thought to have been shot dead by her husband, who then killed himself

Four soldiers, all based at Fort Bragg in North Carolina, are accused of killing their wives.

The murders have all occurred in the past two months, two of them within the past week.

Two of the men later shot themselves, and the two surviving men have since been charged with murder.

'Coincidental'

The base in North Carolina is the headquarters of America's elite Special Forces unit.

Three of the soldiers had recently returned from service in Afghanistan.

One is said to have killed his wife just two days after returning to the US.

Commanders are looking into whether any of the men sought counselling after coming home.

The base's family liaison policy is also now under review.

But a spokesman insisted that, however disturbing, any link between the killings and the war in Afghanistan was purely coincidental.

"We don't have reason to think it was stress-related," US Army Special Operations Command spokesman Ben Abel told French news agency AFP.