GUANTANAMO BAY NAVAL BASE, Cuba – A Pentagon prosecutor Saturday asked a military jury to send both U.S. troops and al-Qaida warriors a message by sentencing confessed Canadian war criminal Omar Khadr to 25 more years of confinement.

An Army attorney for Khadr, captured at 15, said it was time to send the Toronto-born teenage terrorist home from Guantanamo.

“Your sentence will send a message,” case prosecutor Jeffrey Groharing told the jury of seven U.S. officers. “This type of warfare is despicable and reprehensible and there are consequences.”

Khadr, now 24, was captured at age 15 in a 2002 firefight in Afghanistan and Monday pleaded guilty to five war crimes, including hurling a hand grenade that killed a Special Forces medic, Sgt. 1st Class Christopher Speer, during an assault on an al-Qaida compound.

He has spent eight years at Guantanamo and signed a plea bargain with a Pentagon official that the United States would support his return to Canada a year from now to serve out seven more years in a Canadian prison.

But the jury doesn’t know it. Only if it gives him a lesser sentence would the punishment prevail.

So Khadr’s Pentagon defender countered with a plea to let Khadr start his life anew after being raised by an al-Qaida militant father who moved his family between Canada and Afghanistan.

“He’s never had a first chance,” said Lt. Col. Jon Jackson. “Send him back to Canada. Let him start his education, let him start his career. There’s going to be no good in letting him stay here. Send him home.”

Closing arguments included guidance from Judge Patrick Parrish, an Army colonel who said the jury could sentence him to up to life in prison. He also noted that the panel could consider Khadr’s age and other mitigating factors.

The jury is being asked to choose between starkly different views of Khadr in determining a punishment as well as how much of a sign of deterrence it is sending Osama bin Laden’s al-Qaida terror organization.

Khadr’s defender opened with a photo of the boy, smiling at age 8 at a McDonald’s in suburban Toronto, then soon projected a battlefield image.

Another photo showed Khadr at age 15, in the dust of war-torn Afghanistan, his chest ripped apart by two bullets in the back fired by a U.S. commando who captured him.

“Al-Qaida uses kids,” Jackson declared.

That’s precisely why the Pentagon prosecutor urged the panel to give him 25 years, and to send a message: “Your jihad is over.”

Groharing, a former Marine major, acknowledged the youth of Guantanamo’s youngest and last Western captive but noted that even at 15, Khadr spoke four different languages and had already received basic weapons training in Afghanistan.

“Although he was an adolescent, he was mature beyond his years,” Groharing said.

He also offered the jury a different album of children’s photos: Speer, killed at 28, with his then-infant son and 3-year-old daughter, including one on the eve of his 2002 deployment to Afghanistan. Speer, a medic in his assault unit, aspired to study medicine, Groharing said, “and the world will never know” how much good he could have done.

As he spoke, the war court Saturday released the handwritten texts of letters from the Speer children to Khadr. “You make me really sad and mad at you,” wrote 11-year-old daughter Taryn on Oct. 20.

A Pentagon paid expert, Dr. Michael Welner, testified that the Canadian was “highly dangerous” and had not undergone de-radicalization at Guantanamo, which has no such rehabilitative programs.

He invoked his expertise in radicalism and said Khadr was a significant risk because he had memorized Islam’s holy book, the Quran, while “marinating inside a radical Islamic community” inside the prison camps.

Jackson showed the jury a prison camp painting of Khadr’s, a sailboat on a calm sea — and gave them a letter from a Pentagon contract instructor at the prison signed, “Art Teacher.”

He also provided letters from the prison camp’s staff attorneys spanning 2006 until the present that showed Khadr had been a well-behaved prisoner.

Deliberations were expected to last much of the day and could continue until today.