( CNN ) -- Guantanamo Bay detainee Omar Khadr pleaded guilty to charges against him Monday , the Pentagon said , in the first military commission trial there since Barack Obama became president . Khadr , 24 , was accused of throwing a grenade during a 2002 firefight in Afghanistan that resulted in the death of Army Sgt . 1st Class Christopher Speer , a Special Forces medic . He also admitted that he `` converted landmines to Improvised Explosive Devices and assisted in the planting of 10 IEDs with the intent of killing American forces '' in the months before killing Speer , the Pentagon said . Khadr , the youngest detainee at Guantanamo Bay , was 15 at the time . He faced a maximum sentence of life in prison . He pleaded guilty to murder in violation of the laws of war , attempted murder in violation of the laws of war , conspiracy , two counts of providing material support for terrorism and spying in the United States , a Canadian diplomat said . Canada -- where Khadr was born -- has been closely involved in negotiations with the United States over his plea . A source close to the case told CNN on Monday that the deal includes an eight-year prison sentence -- one year in U.S. custody and seven to be served in Canada . Pentagon spokesman Col. Dave Lapan said he expects the sentencing phase of Khadr 's trial to start Tuesday , adding that it probably will finish sometime this week . Details of the plea agreement are not made public , Lapan said , because the seven military officers on the jury `` get the case without any knowledge of the pretrial agreement . They will issue a sentence for the record , and after that -- if the judge allows it -- the pretrial agreement can be revealed . '' If the jury 's sentence is different from the plea agreement , the shorter sentence will be imposed , Lapan said . `` During the next several days , I look forward to proving to the panel and the world that Omar Khadr is a kind , compassionate and decent young man who deserves a first chance at a meaningful life , '' his military defense attorney , Army Lt. Col Jon Jackson , said in an e-mailed statement . The military court in August viewed a 30-minute video that the government said shows Khadr helping to assemble and plant roadside bombs targeting American troops in Afghanistan . The video is undated . The tape was discovered at the compound where Khadr was captured in 2002 , a month after the firefight in which Khadr was seriously wounded and Speer was killed , the military said . The video was allowed into evidence only after a flurry of defense objections , and the judge warned that it was difficult to tell who was speaking at different points on the tape . One of Khadr 's Canadian attorneys indicated last week that he was open to a plea deal . `` He is anxious to avoid a trial before that kangaroo court , '' Nate Whitling said in reference to the U.S. military commission at the Guantanamo Bay , Cuba , detention facility . Catherine Loubier , a spokeswoman for the Canadian Foreign Ministry , offered no details about Khadr 's plea , saying : `` This matter is between Mr. Khadr and the U.S. government , and we will not have further comment on this today . '' U.S. Secretary of State Hillary Clinton reached out to Canadian officials last week as part of an effort to resolve the case , according to two sources . CNN 's Jeanne Meserve , Chris Lawrence , Carol Cratty , Charley Keyes , Elise Labott and Jill Dougherty contributed to this report .
NEW : Plea deal includes an eight-year prison sentence , source says . Omar Khadr , 24 , accused of throwing a grenade that killed a Special Forces medic in 2002 . Khadr was born in Canada , which held negotiations over his plea . It 's the first Guantanamo military commission of the Obama era .