SAN JUAN, Puerto Rico - The U.S. military filed a murder charge yesterday against the Canadian son of an alleged al-Qaeda financier. Omar Khadr, who was detained as a teen in Afghanistan, has spent almost five years at the U.S. military prison at Guantanamo Bay, Cuba.

Khadr, now 20, allegedly joined the Taliban in Afghanistan and threw a grenade that killed a U.S. Green Beret soldier in July 2002. He was captured as he lay wounded after that firefight, at an al-Qaeda compound in eastern Afghanistan.

The U.S. military charged him with murder, attempted murder, providing support to terrorism, conspiracy and spying under rules for military trials adopted last year and first used to try David Hicks, the Australian sentenced to nine months in prison after pleading guilty.

The military said the Toronto-born Khadr would be arraigned within 30 days. He faces a maximum penalty of life imprisonment.

Opponents of the detention center at Guantanamo Bay criticized authorities for subjecting Khadr to the same military-trial system as adult terrorism suspects. In any other conflict, he would have been treated as a child soldier, said Jumana Musa, advocacy director of Amnesty International.

A Pentagon spokesman, Navy Cmdr. Jeffrey Gordon, said Khadr must be held accountable.

The U.S. military said Khadr hurled a grenade that killed Army Sgt. First Class Christopher Speer, 28, of Albuquerque, N.M., and wounded Army Sgt. Layne Morris of West Jordan, Utah. The charges said those acts were carried out "in violation of the law of war," but did not elaborate.

Speer's widow and Morris filed a civil lawsuit against Khadr and his father. In February, a judge awarded them $102.6 million.

Several of Khadr's family members have been accused of ties to Islamic extremists. His Egyptian-born father, Ahmad Said al-Khadr, was killed in Pakistan in 2003 alongside senior al-Qaeda operatives.