As they swarmed through the property and transformed the remote Decker community into a media and sightseeing circus, FBI and other federal agents were hoping for clues that might identify it as the spot where the plot for the Oklahoma attack was hatched and where the massive bomb was put together.
Agents were working against the background of gathering suspicions of a wider conspiracy involving one or several of the many extreme libertarian militia groups that have sprung up in recent years - notably since the government's deadly raid on the Branch Davidian compound in Waco, Texas, two years to the day before the federal office building in Oklahoma City was blown up.
Materials found at the farmincluded some small explosive devices and large amounts of chemical fertilisers and fuel oil.
Mr Nichols was taken into custody at the weekend as a probable material witness in the case and is being held in Detroit before a hearing there tomorrow. His brother, Terry, was also being held as a witness after surrendering last week in Kansas, while the direct suspect Timothy McVeigh remained in custody in Oklahoma City. A fourth man, David Iniquez, was taken into custody yesterday in San Bernardino, California.
At various times, the Decker farmhouse has been home to the Nichols brothers and Mr McVeigh. Neighbours confirmed that the three had all spoken of their defiance of federal government and often passed their time by making small bombs and setting them off.
The men were said to have had contacts with various anti-tax, property- rights organisations in the state, including the Michigan Militia, a paramilitary group that gives its members regular combat training in preparation to defend their so-called constitutional rights, such as gun ownership, from erosion by the government.
The militia, however, has forcefully denied any involvement in the Oklahoma bombing and said the three men had been turned away from the group because their views were too radical. "They are anarchists with extreme terrorist tactics", the militia's leader, Norm Olson, said. "They espoused destruction and assassination."Reuse content