From Drew Griffin, CNN Correspondent

Tapes obtained by CNN of interrogations of a group of U.S. servicemen charged with the unprovoked killings of Afghan civilians describe gruesome scenes of cold-blooded murder carried out under the influence of illegal drugs.

The following is a partial transcript of those tapes, between a military investigator and Cpl. Jeremy Morlock, one of the five U.S. soldier charged with the premeditated murder of three Afghan civilians.

"So we met this guy by his compound, so Gibbs walked him out, set him in place, was like standing here," said Morlock, detailing how, on patrol earlier this year and under the command of his sergeant, Calvin R. Gibbs, he and others took an Afghan man from his home, stood him up and killed him.

"So, he was fully cooperating?" the military investigator asks on the tapes.

"Yeah," Morlock responds.

Investigator: "Was he armed?"

Morlock: "No, not that we were aware of."

Investigator: "So, you pulled him out of his place?"

Morlock: "I don't think he was inside. He was by his little hut area ... and Gibbs sent in a couple of people. He sent Rodriguez off a little ways, far side security. As I said, I'm not even sure Rodriguez knew what was going on and them."

Investigator: "Where did they stand him, next to a wall?"

Morlock: "Yeah, he was kinda next to a wall, so where Gibbs could get behind a wall when the grenade went off and then he kind of placed me and Winfield off over here so we had a clean line of sight for this guy and, you know, he pulled out one of his grenades, an American grenade, popped it, throws the grenade and tells me and Winfield, 'Alright, wax this guy. Kill this guy, kill this guy.' "

Investigator: "Did you see him present any weapons? Was he aggressive toward you at all?"

Morlock: "No, not at all. Nothing, he wasn't a threat."

The Army alleges that three Afghan civilians were killed between January and May of this year.

Morlock's civilian attorney, Michael Waddington, did not deny that his client killed for sport. "That's what it sounds like," he told CNN.

Waddington said his 22-year-old client was brain-damaged from prior IED attacks, was using prescription drugs and smoking hashish and was under the influence of and in fear of his commanding officer, who is also charged.

A hearing is set for Monday for Morlock, the first of five soldiers charged with the premeditated murder of three Afghan civilians. The hearing at Joint Base Lewis-McChord in Washington will determine whether the military has enough evidence against him to proceed with a court-martial.

Some background on the case:

Over this summer, 12 U.S. soldiers were charged for a variety of crimes in what military authorities believe was a conspiracy to murder Afghan civilians and cover it up, along with charges they used hashish, mutilated corpses and kept grisly souvenirs.

Five soldiers face murder charges, while seven others are charged with participating in a coverup. All of the men were members of a 2nd Infantry Division brigade operating near Kandahar in southern Afghanistan in 2009 and 2010.

According to the military documents, Staff Sgt. Calvin Gibbs and four other soldiers were involved in throwing grenades at civilians and then shooting them in separate incidents. Three Afghan men died.

Authorities allege Gibbs kept finger bones, leg bones and a tooth from Afghan corpses. Another soldier, Spc. Michael Gagnon II, allegedly kept a skull from a corpse, according to charging documents. Several soldiers are charged with taking pictures of the corpses, and one – Spc. Corey Moore – with stabbing a corpse.

Five soldiers were originally arrested in June and seven others were charged last month.

The five facing murder charges are Gibbs, of Billings, Montana; Pfc. Andrew Holmes of Boise, Idaho; Winfield, of Cape Coral, Florida; Spc. Michael Wagnon, of Las Vegas, Nevada; and Spc. Jeremy Morlock of Wasilla, Alaska.

The five are from the 5th Stryker Brigade of the 2ID, based out of Fort Lewis, Washington.

In May, CNN reported that the Fort Lewis Stryker Brigade, known as the "5-2," had been the subject of controversy for months inside Army circles. The unit has suffered some of the highest casualty rates of the war. Several senior U.S. Army officials had told CNN there has been a growing belief inside Army circles the brigade was not embracing McChrystal's counter-insurgency strategy and was too heavily focused instead on combat operations.

In one of the most comprehensive analyses of the 5-2's troubled tour in southern Afghanistan, the Army Times reported in January that the brigade commander Col. Harry Tunnell replaced one of his company commanders whose group had suffered high casualties.

But the Army Times, a privately-published newspaper, quoted several soldiers who said that company commander was very popular with the troops, and that the unit's deep-set troubles and casualties resulted from a lack of training for the type of counter-insurgency warfare now being called for.

"What we're doing is not working, and we need to go on a different tack," the Army Times quoted one soldier as saying.

A senior U.S. Army official directly familiar with Stryker operations said the command of the 5-2 has been a concern to the Army for months.

MORE

• May 24, 2010: Sources: U.S. soldiers focus of criminal investigation

• June 16, 2010: Army charges 3 more in Afghan civilian killings

• August 26, 2010: U.S. soldiers charged with conspiracy in killings

• September 9, 2010: Army: 12 soldiers killed Afghans, mutiliated corpses