Last month, Sgt. Eric Colvin's (search) testimony helped convict a fellow soldier of killing two other Fort Riley soldiers. Now Colvin faces his own court-martial.

Colvin, 24, is charged with two counts of premeditated murder for the Sept. 13, 2004, shooting deaths of Staff Sgt. Matthew Werner, 30, and Spc. Christopher D. Hymer, 23, at a farmhouse about 30 miles west of Fort Riley (search).

A court-martial for Colvin, of Papillion, Neb., was scheduled to begin Wednesday at Fort Riley and was expected to last one day. Colvin hasn't entered a plea to the charges.

Another soldier, Sgt. Aaron Stanley (search), has already been sentenced to life in prison for the shootings. Stanley, 23, was found guilty of two counts of premeditated murder. Stanley confessed in court to the shootings but claimed the acts were in self-defense.

Prosecutors said Stanley shot the two men to conceal an illegal drug trafficking operation, believing the victims to be informants for Fort Riley police. Stanley and Colvin had acknowledged manufacturing methamphetamine and growing marijuana at the farmhouse.

At his court-martial, Stanley said he shot Hymer after the soldier opened fire on him first and shot Werner after finding him fighting with Colvin and trying to stab him. But Colvin, a key prosecution witness, testified he watched Stanley stand over the two victims and shoot.

All four soldiers were part of the 1st Battalion of the 41st Infantry Regiment, 3rd Brigade, 1st Armored Division based at Fort Riley. Both Stanley and Colvin were with Bravo Company and had served in Iraq.

Colvin also faces charges of conspiracy to commit murder, use of methamphetamines, possession of marijuana with the intent to distribute and wrongful distribution of methamphetamines.

Colvin testified previously that he sought treatment for methamphetamine addiction and suffered from post traumatic stress disorder, spending a month in a Veterans Affairs hospital for treatment in April 2004.