U.S. officials are turning to modern forensic science — DNA testing —- in hopes of determining whether Usama bin Laden is dead or alive.

Government sources said Wednesday that officials want to compare human remains found at bombing sites in Afghanistan against DNA samples from the terrorist leader's family.

The sample could come from any of a number of bin Laden relatives. Samples from his mother's side of the family could provide the most certain match, though those from his father's side could provide a close match as well.

While bin Laden is believed to be the only child of the union of Mohammed Awad bin Laden and a Syrian woman, he has dozens of half brothers and half sisters.

Bin Laden's father, who is dead, had 54 children by several wives. The family runs a prominent construction conglomerate based in Saudi Arabia, and has publicly disowned bin Laden for many years.

A New York spokesman for that part of bin Laden's family, Tim Metz, said he was unaware of the government making any formal request to family members for samples. He suggested samples could be obtained from hospitals or other sources.

Bin Laden's mother apparently now has little association with the bin Laden family. She is believed to live in Saudi Arabia and to have remarried and had children by that marriage.

Requests for DNA samples may be a culturally sensitive matter in Saudi Arabia, where family privacy is sacrosanct.

The remains to be tested in Afghanistan include those found at the site of a Feb. 4 missile strike by a CIA-operated Predator drone, military officials said. The target was a meeting of suspected leaders of Al Qaeda, the terror network headed by bin Laden.

The government has been interested in DNA samples from bin Laden's family for months and stepped up the effort following the Predator strike, a law enforcement official said Wednesday.

Defense officials have said for months that they are unsure if bin Laden is alive. In the past month, U.S. intelligence obtained faint signs that he was alive and somewhere in the Pakistani-Afghan border region, a U.S. official said.

It is unclear how or from whom the U.S. intends to obtain the genetic material. In theory, it wouldn't take much — a blood specimen, a scraping from the inside of the mouth, even a hair follicle could provide enough DNA for a match.

A State Department official said no request for DNA from bin Laden's family was delivered to Saudi Arabia through State Department channels. Gen. Peter Pace, vice chairman of the Joint Chiefs of Staff, said he was unaware of any such effort.

The DNA collection effort isn't simply to determine who died in the Predator strike; other remains found after U.S. bombing strikes in Afghanistan have yet to be identified, one official said.

U.S. officials suspect the three people killed by the Feb. 4 Predator strike in the Zawar Kili area of eastern Afghanistan were terrorists. The heavy security and deferential treatment given a central figure suggest it may have been an Al Qaeda gathering.

Some Afghans, however, say the strike killed innocent scavengers.