The 44-year-old former US Army Green Beret has been under a military-style siege for more than nine days near Naples, a hamlet in a remote and heavily forested region near the Canadian border that has long been the refuge of white racists and bizarre religious cults.
The first sign of a breakthrough came this weekend, when Mr Weaver told a mediator, Lt-Col James 'Bo' Gritz, a fellow former Green Beret who once hunted for US prisoners of war in South-East Asia, that he was considering giving himself up. Col Gritz said Mr Weaver wanted time to pray.
Mr Weaver and his family retreated to the cabin 18 months ago after he failed to appear in court to answer accusations of selling sawn-off shotguns to an FBI informer who was investigating gun operations involving white racist groups. But the siege only began in earnest when a federal marshal, an expert in Swat-team operations, was shot dead on Mr Weaver's property during a gun-fight on 21 August.
Almost 200 state and local police, FBI agents and marshals moved in, supported by helicopters and armoured vehicles, and set up barricades below Mr Weaver's heavily wooded homestead. To the horror of the authorities, scores of angry people - including other white supremacists - gathered in a show of support for the Weaver family.
Last night Kevin Harris, 24, who is charged with the marshal's murder and had also been under siege in the log cabin, surrendered to get medical attention for gunshot wounds. He was escorted from the cabin by Col Gritz.
Mr Weaver's 13-year-old son and wife died of gunshot wounds. Also inside the cabin are Mr Weaver's three daughters, who include a nine-month-old baby.
The intervention of Col Gritz, an ultra-right independent candidate in the coming presidential election, has led the FBI to hope that they will be able to negotiate directly with Mr Weaver, who is heavily armed.