Omar Khadr may have been a fresh-faced 15-year-old kid when he was captured for the alleged murder of a U.S. army medic, but he is also a killer, according to the prosecutor working on his case.

Prosecutor Moe Davis, who described the Canadian teen as a terrorist murderer, is attempting to prove Khadr's guilt in Guantanamo Bay, where Khadr has been held since his capture in 2002. Khadr's pre-trial hearing begins Wednesday before a U.S. military tribunal.

That pre-trial will be the first time Canadians have seen Khadr since he was picked up and put in custody in Guantanamo Bay.

Davis is angry that Khadr -- accused of throwing a grenade at a U.S. medic, killing him and blinding another -- is being sympathetically portrayed.

"You will see evidence that the smiling face of Omar Khadr as he builds bombs to kill Americans," Davis said.

"You'll hear about Chris Speer who was murdered by Mr. Khadr. Thanks to American medics who stepped over their dead friend, Khadr is alive today."

Davis said the 19-year-old should be tried by a U.S. military tribunal despite claims that the process is flawed. He defended the controversial American system and said the law needs to grow to deal with new societal threats like terrorists.

Khadr's lawyers are trying to shut down the proceedings claiming that Guantanamo detainees are not getting their rights of due process granted under international law.

The military commissions are being challenged in the U.S. Supreme Court as unconstitutional, and some experts say the trial is a farce, especially since the military appointed its own rookie lawyer to defend Khadr.

"This is not a fair process, no matter how you dress it up this military commission is still a sham," Muneer Ahmad, a U.S. lawyer and professor said.

"A lawyer who's never defended a client even on charges of jaywalking, it would be laughable if the stakes weren't so high."

Critics claim Khadr was tortured into confessing,

Avi Cover, of Human Rights Watch, said Khadr has endured having pine solvent poured over him, threats of rape, and has been allowed to defecate on himself during his stint in Guantanamo Bay.

The U.S. has denied using such tactics, and points to the Khadr family tree. His father was a close associate of Osama bin Laden, and he and his brothers admit having spent time at terrorist training camps.

Khadr, who was captured at age 15, is facing a murder charge for the July 2002 death of a U.S. Army medic. Sgt. 1st Class Christopher Speer died 11 days after being injured by a hand grenade allegedly thrown by Khadr.

Charged in November with murder, attempted murder, conspiracy and aiding the enemy, Khadr faces life in prison after U.S. authorities said they wouldn't pursue the death penalty.

Wednesday's hearings will be similar to an arraignment. Ottawa has said officials will observe the proceedings, but they are unable to intervene.

The Khadr family has provoked intense debate in Canada. The family patriarch, Ahmed Said, believed to be a close associate of bin Laden's, was killed in a gun battle with U.S.-led coalition forces in Pakistan in October 2003.

One son, Karim, was paralyzed in the incident and returned to Canada with his mother in April 2004 to get medical treatment.

Another brother, Abdurahman, was once detained at Guantanamo but was released and went back to Canada.

Meanwhile, the extradition hearing for another brother, Abdullah Khadr has been put over until Feb. 2.

The Americans accuse the 24-year-old of conspiring to kill U.S. citizens abroad. He was arrested on Dec. 17 on a provisional arrest warrant issued by the United States.

With a report from CTV's Joy Malbon in Guantanamo Bay