Joint Base Lewis-Mcchord , Washington ( CNN ) -- A military judge sentenced a soldier accused of being part of a rogue Army `` kill squad '' that murdered civilians in Afghanistan to three years in military prison and to receive a bad-conduct discharge Friday . At the opening of his court martial for allegedly killing civilians in Afghanistan , Army Specialist Adam Winfield pleaded guilty to manslaughter and use of an illegal controlled substance . Winfield is one of six soldiers from the 5th Brigade , 2nd Infantry Division who , while on assignment in Afghanistan , are accused of participating in illegal killings of civilians and covering up the alleged crimes by making it appear as if they were insurgents . An additional six soldiers are accused with lesser crimes in the case , including helping to cover up the killings . Winfield originally faced five charges including murdering three Afghan civilians , but Friday accepted a plea agreement with prosecutors to plead guilty to lesser charges and agree to testify against other soldiers in the case . He faced a maximum of 17 years behind bars . With time already served , Winfield will serve about two more years and will be demoted to the rank of private . He will also receive a bad-conduct discharge , rather than the more severe dishonorable discharge . During his testimony Friday , Winfield told the military court that he was afraid of his Staff Sergeant . He said Sgt . Calvin Gibbs concocted `` scenarios '' where the men would select Afghan civilians to murder and then place weapons on them so they would appear to be insurgents who had attacked U.S. forces first . During a May 2010 mission to a village called Qualaday , Winfield testified that Sgt . Gibbs pointed to an unarmed Afghan man . `` Is this the guy ? '' Winfield testified Gibbs asked him and Pvt . Jeremy Morlock . `` I had an idea that Sgt . Gibbs was looking for a kill , '' Winfield testified . The soldiers separated the man from his wife and young children , Winfield said . Then , he said , they killed the man by throwing a grenade at his feet and shooting him . They later claimed the Afghan man had thrown the grenade at them . Winfield said Friday he fired his automatic weapon away from the man as to pretend to have taken part in the alleged murder . But he admitted he did nothing to keep his fellow soldiers from carrying out the alleged execution of an unarmed civilian . `` I did n't say no , I did n't object to it , '' Winfield told the court . Winfield said the group 's alleged ringleader , Sgt . Gibbs , was concerned he would talk about the alleged murders . Gibbs , Winfield said , threatened that he could kill him and make it look like an accident had taken place while Winfield was repairing a vehicle or working out in the gym . When Winfield went to speak with an Army Chaplain about depression he was suffering from , he said Gibbs intercepted him . `` Sgt . Gibbs reminded me I should n't be talking about things I should n't be talking about , '' Winfield testified . Although Winfield said he was pressured to keep quiet , he testified no one forced him to take place in the alleged killings . `` If I had done my duty , he would still be alive , '' Winfield said , referring to the Afghan man he said his fellow soldiers murdered . In March , another soldier , Pvt . Morlock , pleaded guilty to killing that man and two other Afghan civilians for thrills and covering up the murders . Morlock 's chilling testimony painted a picture of soldiers gone rogue -- abusing drugs , executing Afghan civilians they referred to as `` savages '' and posing in photographs over the dead men . Morlock is serving a 24-year sentence in prison . Sgt . Gibbs , who also faces court martial in the case , has said the killings were justified under Army rules of engagement . Gibbs is also accused of taking body parts from the dead men to keep as grisly souvenirs . Winfield 's father , Christopher Winfield , previously told reporters that his son had told him about the alleged killings and that he was afraid that his fellow soldiers might target him for speaking out . Christopher Winfield said he tried to report the group 's alleged actions to the Army but was ignored . The Army has said it is investigating the claims made by Winfield 's father that he tried to alert officials about the alleged murders . During testimony Friday , both of Winfield 's parents lashed out at the Army for what they called a failure to act on the information they had provided . But Emma Winfield said her son takes responsibility for his part in the alleged murders . `` Adam definitely understands the error that he made , '' she said . `` He is filled with remorse . '' In halting testimony before he was sentenced , Winfield told the court : `` I was sorry for what happened here , I wish it did n't go the way that it did , '' he said . `` I wish I had been braver . ''
NEW : Adam will receive a bad-conduct discharge . He is accused of being three of six soldiers who formed a `` kill squad '' Winfield originally faced three charges including murdering six Afghan civilians . Winfield 's father said he tried to report the group 's alleged actions to the Army but was ignored .