Media playback is unsupported on your device Media caption Two former colleagues of Staff Sgt Calvin Gibbs testified to army investigators, giving evidence about the alleged self-styled "kill team"

An Army staff sergeant charged with killing three Afghan civilians admits taking fingers off bodies as war trophies, his lawyer says.

Staff Sgt Calvin Gibbs, 26, maintains he was not involved in the killings, and has pleaded not guilty to 16 criminal charges.

He is one of five soldiers charged.

In March 2011, photographs were published showing the soldiers posing with the corpses of Afghan civilians they had allegedly just killed.

The admission that Sgt Gibbs took fingers off the three victims and either kept them as war trophies or gave them to others involved in the killings came during Monday's opening statements from Sgt Gibbs' lawyer, Phil Stackhouse.

'Out of control'

Mr Stackhouse told jurors at the court martial that Sgt Gibbs believe the three killings had been legitimate engagements and that he had been conspired against by his co-defendants.

Military prosecutor Capt Dan Mazzone said Sgt Gibbs had killed simply because he wanted to kill.

He told jurors that the accused also led a group in assaulting a soldier who reported drug use in the unit, and that he threatened the same soldier.

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

Three within the platoon have pleaded guilty and agreed to testify that it was Sgt Gibbs' idea to kill civilians and stage the deaths to make them appear to have been combatants.

Sgt Gibbs is accused of providing a grenade used in January 2010 to kill the first victim, an unarmed farmer in a field in Kandahar, to shooting or tossing grenades at the next two in February and May of that year.

He faces up to life in prison without parole if convicted.