Michael Wagnon testified that he only shot his gun in defence during Afghan deployment in which civilians were killed for sport
The US military has dropped all charges against the fifth soldier it had accused of killing Afghan civilians for sport during a 2010 deployment.
Specialist Michael Wagnon, 31, had been charged with the unlawful killing of one Afghan civilian in February 2010. He was expected to go on trial in March.
Four other soldiers from a Lewis-McChord Stryker brigade have been jailed in connection with the killings of three unarmed men during patrols in Kandahar province.
In all, 12 soldiers were charged in connection with alleged misconduct that, in addition to murder, included smoking hash, collecting illicit weapons, the mutilation and photography of Afghan remains and the gang-beating of a soldier who reported the drug use. Eleven soldiers were convicted on various counts.
An army investigating officer had twice recommended that prosecutors dismiss the case against Wagnon.
The case hinged on an account from a "kill team" participant, Specialist Jeremy Morlock, who is serving 24 years after admitting his involvement in all three killings. Morlock testified that Wagnon knowingly participated in a scheme to kill a civilian.
Wagnon had testified that he shot at an Afghan on the day in question because he believed the man had fired a weapon at Staff Sergeant Calvin Gibbs. In November, Gibbs was sentenced to life in prison over the killing of three Afghans, including the man in the February 2010 encounter.
Wagnon "was simply a soldier pulling security who responded to the firing of weapons and came to support another soldier", Vokey said. "That's all Michael Wagnon ever did."
In a statement, the Lewis-McChord joint base said the charges were dismissed "in the interest of justice".
Wagnon was released from custody last June. He has been living unrestricted at the base and working as a soldier, his lawyer, Colby Vokey said.
Wagnon was ecstatic at the news, "very, very relieved" and eager to tell his wife, Vokey said.
"The witnesses coming forward that we were able to speak to all confirmed the same thing – that Michael Wagnon had nothing to do with any kind of illegal activity."
An army spokesman, Lieutenant Colonel Gary Dangerfield, said Wagnon "should be able to continue his normal duties as a soldier".