An Afghan who died in U.S. military custody last year complained that he was bitten by a snake hours before an army medic found his lifeless body, an American commander said Monday, rejecting suggestions that the man had been mistreated.

Sher Mohammed Khan (search) died in September at Camp Salerno (search), an American base in the eastern province of Khost. U.S. forces detained him during a raid on his home in which his brother was fatally shot.

Col. Gary Cheek (search), the commander of U.S. forces in eastern Afghanistan, said Khan had complained to a guard the evening he died that a snake had bitten him. A military doctor examined him and found no evidence of a bite, but ordered a medic to check on him during the night.

"The second time the medic went back to check on him, that's when they found that he was no longer breathing," Cheek said at a news conference.

Doctors at the base's hospital were unable to revive Khan. Cheek said he had yet to receive the results of an autopsy.

"While I would say that it's a regrettable incident, I was confident then and I am confident now that we're treating every detainee with dignity and respect," Cheek said.

He also said U.S. troops shot Khan's brother after he opened fire on one of the soldiers.

Human Rights Watch (search) last month cited Khan's case in an open letter to Secretary of Defense Donald H. Rumsfeld accusing the Pentagon of dragging its feet on clearing up the circumstances in which at least eight detainees have died in Afghanistan.

Khan's family told Afghan rights investigators his body had bruises when they retrieved it from the base, Human Rights Watch said.

At the time, the Army's Criminal Investigation Division (search) said it had discovered "no signs of abuse or trauma" in Khan's case. A U.S. defense official as well as the governor of Khost province said Khan was believed to have died of a heart attack.

Cheek said the forces under his command, which stretches across 16 provinces, would be "relentless" in their pursuit of insurgents through the bitter Afghan winter. He said they were tracking about 20 militant leaders inside Afghanistan, but didn't identify any of them.

But he said U.S. troops were taking as few prisoners as possible to try to win stronger support from the local population, and following a review of policy on detentions. "I've told our commanders, for example, to minimize the number of Afghan nationals or others that they detain."

There were usually no more than 10 prisoners in the three detention facilities in his region, he said. All were currently empty.

Those not quickly released are transferred to larger jails at U.S. bases in Bagram and Kandahar, from where many have in the past been sent to the American jail for terrorism suspects at Guantanamo Bay, Cuba.

Cheek, who took charge of U.S. operations in eastern Afghanistan last June, ruled out the possibility that any prisoners were being abused under his command.

"If we were to treat those we detain poorly, it would really hurt our overall attempts to win the confidence and trust of the population, so it makes no sense for us to abuse prisoners and I will tell you that we do not do that," he said.