FBI headquarters officials in Washington were so concerned that white separatists at the Elohim City compound in Muldrow, Okla., might lash out on April 19, 1995 -- the day Timothy McVeigh did choose -- that a month earlier they questioned a reformed white supremacist familiar with an earlier plot to bomb the same federal building that McVeigh targeted.

"I think their only real concern back then was Elohim City," said Kerry Noble, the witness questioned by the FBI on March 28, 1995 -- just a few weeks before McVeigh detonated a truck bomb outside the Alfred P. Murrah federal building, killing 168 people, including 19 children.

Noble told The Associated Press that his FBI questioners appeared particularly concerned about what Elohim City members might do on April 19 because one of their heroes, Wayne Snell, was being executed that day and another, James Ellison, was ending his parole in Florida. FBI officials confirmed Noble's account.

Snell, Ellison and Noble had plotted to attack the Murrah building in 1983 with plastic explosives and rocket launchers, according to Noble and FBI officials. The plan never reached fruition.

In the days before his execution for murder, Snell also began making threats from his Arkansas prison that there would be a bombing or explosion on April 19 to avenge his death, according to prison and FBI officials.

"Some of the corrections officers heard (Snell) in a visitors room talking with people, saying there would be a large explosion or event of some type. He said the immediate reaction would be to blame it on Middle Eastern types. This was prior," said Alan Ables, a former Arkansas corrections official.

The Bureau of Alcohol, Tobacco and Firearms had an Elohim City informant who disclosed before the bombing that white supremacists were "preparing for a war against U.S. government."

The ATF informant also would tell the FBI shortly after McVeigh's bombing that Elohim City members had specifically discussed targeting federal buildings in Oklahoma for "destruction through bombings."