Updated

Army prosecutors filed charges Tuesday against a sixth Washington state-based soldier in a plot to murder Afghan civilians for sport during patrols in Kandahar province last year.

Staff Sgt. David Bram, of Vacaville, Calif., faces charges that include solicitation to commit premeditated murder, aggravated assault on Afghan nationals, failing to report crimes including murder, planting evidence and unlawfully discussing murder scenarios with subordinates.

Prosecutors say the soldiers from Joint Base Lewis-McChord, south of Seattle, killed three Afghan civilians during patrols, in each case by finding isolated men, pretending they posed a threat, and slaughtering them with guns or grenades. They are accused of planting weapons by the bodies to give the appearance that the victims were combatants, and one soldier, Staff Sgt. Calvin Gibbs of Billings, Mont., is accused of keeping fingers as war trophies.

One of the defendants, Spc. Jeremy Morlock of Wasilla, Alaska, has pleaded guilty in a deal to testify against his co-defendants and was sentenced to 24 years in prison. The others are awaiting courts martial or other hearings; Gibbs maintains all the killings were legitimate.

Army Maj. Kathleen Turner, a spokeswoman for the base, said she did not immediately have further details about the charges filed against Bram or know the identity of any civilian lawyer who might be representing him. Bram faces up to 21 years if convicted as charged.

Bram referred questions to his attorney, who did not immediately return a call seeking comment.

Bram, 27, had previously been among seven soldiers from the unit who faced misconduct charges unrelated to the killings, including allegations of beating up a soldier who blew the whistle on drug use by his colleagues.

But in his plea agreement, Morlock claimed Bram's involvement went beyond that. He told prosecutors that several times Bram overheard Gibbs discussing situations in which they might kill civilians, and moments before the first killing, on Jan. 15, 2010, Morlock asked Bram whether it was "clear" to stage the killing of an unarmed man in a field.

"Bram communicated that it was clear to implement the scenario to kill the unarmed Afghan male," the plea agreement reads.

The plea agreement did not specify whether Morlock was asking for permission from Bram or asking him whether any possible witnesses were present.

Defense attorneys have claimed that Morlock implicated other soldiers to curry favor with prosecutors and win a more favorable plea deal. They note that while Morlock claims two of the defendants, Spc. Michael Wagnon II, of Las Vegas, and Pvt. 1st Class Andrew Holmes, of Boise, Idaho, knowingly participated in two of the killings, no evidence has emerged publicly to corroborate his accounts.

In each of the three killings, Morlock or Gibbs is accused of killing the civilians while being supported by one of the other defendants.

Both Holmes and Wagnon insist they fired while rushing to help colleagues they believed to be under enemy fire. A military investigator recommended dropping the murder charge against Wagnon, and Holmes this week was granted a new preliminary hearing after a forensic expert testified that his weapon did not cause the death of the man he's accused of killing.

The other defendant in the case is Spc. Adam Winfield of Cape Coral, Fla.