The four men accused of conspiring to bomb two Jewish sites in the Bronx and shoot down military aircraft in Westchester appeared before a judge Friday for a preliminary hearing.

James Cromitie, David Williams, Onta Williams and Laguerre Payen, of Newburgh, pleaded not guilty Wednesday to a slew of conspiracy charges, including conspiring to use weapons of mass destruction and acquire and use anti-aircraft missiles to attack planes at the Stewart Air National Guard base in Newburgh.

The four suspects were taken into custody May 20 after allegedly planting what they thought were bombs in front of Riverdale Temple and Riverdale Jewish Center in the Bronx. Investigators say the mock explosives were provided to the suspects by an FBI informant.

During Friday's hearing at the White Plains Federal Courthouse, Payen's attorney claimed her client could not have been involved in the alleged plot because he suffers from a bipolar disorder and schizophrenia. The lawyer asked to evaluate Payen?s mental condition to determine whether he can stand trial.

However, prosecutors insist Payen is merely acting. They say they have hours of video recordings showing the suspects, including Payen, discussing the details of the terror plot and mapping out how to shoot down planes at Stewart Airforce base, which the suspects allegedly referred to as "ground zero."

David Williams, the father of the suspect by the same name, claims his son and the other three men were entrapped by the FBI.

"My son takes mass transit, doesn't have a vehicle, doesn't drive," Williams says. "He doesn't even own a bicycle. How could he obtain resources to pull this stunt off?"

Defense attorney Suzanna Drodery believes the prosecutions want to sway public opinion by using the recordings.

"They want to get public sympathy going, public outrage going," she says. "It's a highly explosive case."

The suspects' next court appearance is scheduled for Sept. 17. If convicted, the four men face life behind bars.