A federal magistrate Tuesday ordered an ex-convict with an apparent grudge against the court system to stand trial for allegedly plotting to blow up the federal courthouse in downtown Chicago.

Federal Magistrate Morton Denlow said prosecutors had established probable cause in the case against Gale William Nettles (search), 66, who was arrested last week with what prosecutors said was a pickup truck containing 1,500 pounds of fertilizer he allegedly thought was ammonium nitrate (search), a farm chemical used to blow up the Oklahoma City federal building.

Prosecutors have said Nettles had planned to sell the chemical to terrorists whom he wanted to carry out a plot to blow up the Dirksen federal building. Everyone else involved, however — including the "terrorists" and the people who sold him the fertilizer — were cooperating witnesses or federal agents.

Denlow also ordered Nettles held without bond, saying he believed Nettles was "somewhat unstable."

During Tuesday's hearing, FBI (search) Special Agent Sonjia Wing testified Nettles was in a Mississippi prison last year for counterfeiting when he asked a fellow inmate if he could help him obtain ammonium nitrate to blow up a building.

The inmate gave Nettles a telephone number of someone Nettles believed could help him. The person was an FBI agent in Louisiana, Wing said. Nettles was released in October 2003.

After Nettles' release from prison, according to Wing, he telephoned the number and was later called by a federal agent posing as someone who had access to the fertilizer.

Describing the sting operation, Wing said Nettles allegedly bought what he believed was ammonium nitrate but was actually a non-dangerous fertilizer.

An undercover agent delivered 500 pounds of the fertilizer to Nettles at a warehouse, then delivered the pickup truck with another 1,500 pounds of fertilizer to a Chicago park and met Nettles, she testified.

Nettles was arrested last Thursday at the park when he met the undercover agents posing as terrorists and accepted $10,000 from them.

In a possible preview of what he will argue at trial, Nettles' attorney, John T. Theis (search), suggested Nettles was set up, and that it was the agents who initiated the plot and pushed it along.

Wing acknowledged not only did federal agents place calls to Nettles, but they also obtained equipment he needed to start counterfeiting money again.

But Denlow dismissed what he said was Theis' suggestion Nettles would not have been charged had agents not contacted Nettles.

It was Nettles' first phone call to the federal agent that "in effect, started the ball rolling," the judge said.