Staff Sergeant Calvin Gibbs exploited a lawless platoon culture when he directed plans to execute innocent Afghanistani civilians and disguise the killings as combat engagements, prosecutors charged at the start of Gibbs' court martial.

The trial is the culmination of an investigation into the killings of three different Afghanistani civilians, including a 15-year-old boy. Three other soldiers charged in connection with the grisly scheme the probe have already pleaded guilty and offered testimony implicating Gibbs as the ringleader. Prosecutors detailed how soldiers would stage combat by hurling grenades or planting weapons on corpses of unarmed Afghanistanis.

In a prior confession, U.S. Army Specialist Jeremy Morlock described how members of the 5th Stryker Brigade formulated plans to kill Afghanistani civilians during hashish-fueled conversations, guided by Gibbs' reassurance about some of the stuff that he had gotten away with during a previous tour in Iraq. The desire to kill grew in part out of frustration with a counterinsurgency strategy that relied on fostering good relations with locals, Morlock testified on Monday.

The whole idea of the infantry mindset is to get into firefights and engage the enemy, Morlock said.

Defense Says Trial Is Betrayal of an Infantryman

The controversy gained widespread notoriety when the German magazine Der Spiegel published photos of soldiers proudly posing with corpses, followed by revelations that members of the so-called kill team kept severed fingers as souvenirs. Gibbs' lawyer, Kevin Stackhouse, confirmed that Gibbs had cut fingers off of slain Afghanistanis but maintained that they were to be used as biometric data on a combatant.

These people had tried to kill him, Stackhouse said. He also portrayed the trial as an attempt to scapegoat an innocent soldier, calling the case the ultimate betrayal of an infantryman.

The gruesome allegations have raised serious questions about the extent to which the platoon's leaders had knowledge of the situation. A separate Army investigation faulted Colonel Harry Tunnell, who while serving as commander of the 5th Stryker Brigade frequently mocked the counterinsurgency strategy of delivering aid and protecting civilians and instead advocated a combat-oriented approach of search and destroy. But while the investigation said discipline had deteriorated to an alarming extent it concluded that leadership was not responsible, noting that the incidents were not reported above the platoon level.

While the alleged criminal acts may have been identified earlier or perhaps prevented with stronger leader presence, the report's author, Brig. General Stephen Twitty wrote, I found nothing to indicate that the alleged criminal acts occurred as a result of the command climate set by the leaders above them.

Prosecution: It Was Premeditated Murder

But prosecutor Dan Mazzone said that Gibbs was able to take advantage of an ineffective hierarchy and weak morale in pursuing his designs of premeditated murder.

This platoon is out of control, Mazzone said. He sees weak leaders, he sees an opportunity, he sees soldiers who are willing to cross the line.

A similar narrative emerged at Morlock's trial, which resulted in Morlock receiving a 24-year sentence after pleading guilty. The 5th Stryker Brigade had been ravaged by injuries, including the man who Gibbs would replace having his legs shorn off by an improvised explosive device, and anger soared. Prior to his conviction, Morlock told Rolling Stone that they started taking things into our own hands because of operating in such bad places and not being able to do anything about it.

In a dysfunctional unit, we cannot predict who will be the deviant - but we can predict deviance, sociologist Stjepan Mestrovic testified at Morlock's trial.

In a Facebook chat with his father, Spc. Adam Winfield -- who would later plead guilty to participating in one of the killings -- complained that people in his platoon could get away with 'murder' and added that pretty much the whole platoon knows about it. Pfc. Justin Stoner, who initially complained to superiors about pervasive hashish smoking and later informed them about the kill team, said Gibbs and Morlock showed him severed fingers and warned him that he would suffer the same fate if he spoke out.

Probably about a month afterward, the majority of the platoon had figured out one way or another what had really happened, an anonymous member of the platoon told the New York Times Magazine. See no evil, hear no evil: that's the mentality, the soldier added.

You can contact the reporter at j.white@ibtimes.com