Spc. Jeremy Morlock pleaded guilty Wednesday morning to three counts of murdering unarmed Afghans and other wrongdoing in an important juncture in a U.S. Army war-crimes investigation.

As part of the plea agreement, Morlock is expected to receive a prison sentence of up to 24 years, and to testify against other soldiers accused of crimes while serving in Afghanistan, including four accused of murder. The plea resulted from months of negotiations with prosecutors, and must now be approved by an Army judge.

Morlock attended the court-martial in dress uniform, answering “”Yes, sir”” and “”No, sir”” in a quiet voice to a series of questions about his understanding of the plea agreement from the Army judge, Lt. Col. Kwasi Hawks. During the questioning, the judge asked Morlock whether he shot people to scare them and it got out of hand, or if the plan was to kill people.

“”The plan was to kill people,”” said Morlock, who had deployed to southern Afghanistan with the 5th Brigade, 2nd Infantry Division.

Much of the courtroom gallery was filled by Morlock’s family and friends, who had flown down from Alaska. Witnesses scheduled to testify during the court-martial include Audrey Morlock, the soldier’s mother, and James Smith, his former hockey coach.

At Wednesday’s court-martial, he pleaded guilty to conspiring and then carrying out the three murders in January, February and May 2010. In a stipulated agreement, he said that the deaths were staged, with grenades or weapons dropped by the corpses to make them appear to be legitimate combat deaths.

Morlock also pleaded guilty to helping beat up another soldier who had blown the whistle on hashish smoking by some members of his platoon, and later joining a squad leader, Staff Sgt. Calvin Gibbs, to drop human fingers on the floor in front of that soldier.

In his stipulation of facts that detail war crimes, Morlock portrays Gibbs as a ringleader who joined the unit in November 2009 and quickly began talking about “”scenarios”” to kill unarmed Afghans.

Gibbs says he is not guilty of murder, and maintained that all the deaths were the result of combat actions. If Morlock’s plea deal is finalized, he is expected to be a key witness for prosecutors at Gibbs’ court-martial, expected later this year.

Morlock has gained considerable notoriety through leaks to the media of a videotaped interview with investigators in May 2010, in which he detailed the murders. Then earlier this week, the German news organization Der Spiegel, in a story about the platoon, published a photo off Morlock kneeling next to the body of the man he killed in January 2010.

Without a plea deal, Morlock would risk a sentence of life imprisonment without parole. If he receives a sentence of 24 years, he would be eligible for parole after serving as little as eight years.

Audrey Morlock, Morlock’s mother, blames much of her son’s plight on a failure of Army leaders who deployed her son to Afghanistan.

“”I think the government is just playing these guys as scapegoats,”” she said in an earlier interview. “”The leaders dropped the ball. Who was watching over all this?””