Jeffery Smith recalled how his Army unit beat and humiliated Iraqi prisoners. Former Marine Bryan Casler recounted how fellow Marines urinated and defecated into food and gave it to Iraqi children. Former Marine Matthew Childers talked about how he used to humiliate Iraqi civilians during predawn raids on their homes. When he described turning away an Iraqi father who was asking American troops to help the badly burned baby he carried in his arms, Jackson began to weep silently. These soldiers are saying: 'I'm complicit,' " said [Liz] Jackson, 29, a community organizer from Cambridge. "But every American citizen who saw this happen and isn't out there protesting is complicit. I include myself." Hundreds of soldiers and Marines from across the country are testifying this weekend in the "Winter Soldier: Iraq and Afghanistan" hearings, a four-day event held at the National Labor College in Silver Spring, Md. The event is named after the 1971 Winter Soldier hearings in which Vietnam War veterans testified in a Detroit hotel about war crimes they had participated in or witnessed. The hearings, which began Thursday and end today, were organized by the Iraq Veterans Against War, a national antiwar organization, and broadcast live in locations across the country. The veterans who testified called for an immediate withdrawal of US troops from Iraq. On Friday, more than a dozen Iraq and Afghanistan veterans from Massachusetts drove to Silver Spring to observe and participate in the hearings. One of them, Ian J. Lavallee, an Iraq war veteran from Jamaica Plain, said in a phone interview, "We dehumanized people. The way we spoke about them, the way we destroyed their livelihoods, their families, doing raids, manhandling them, throwing the men on the ground while their family was crying. I became a person I never thought I would become," he said.