ALBANY, N.Y. (CBSNewYork/AP) — FBI agents acknowledge they didn’t initially know if an upstate New York man was serious when he talked about assembling a mobile X-ray device to sicken or kill Muslims — or if he was even capable of it.

Testifying Tuesday in federal court, Special Agent Chris West and an undercover operative identified only as Special Agent Jeff said they were trying to determine those answers in 2012 and kept contacting Glendon Scott Crawford about the proposal, even offering to provide components so he wouldn’t turn somewhere else.

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Crawford and another man, Eric Feight, 54, wanted to build a mobile, remotely operated device that would silently zap unsuspecting targets with lethal doses of X-rays, prosecutors said. The harmful effects of the lethal radiation would only surface days after the exposure, prosecutors said.

Crawford, 49, has denied the charges, including conspiracy to use a weapon of mass destruction.

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His attorney says Crawford, an industrial mechanic, was targeted in an elaborate FBI sting and that no crime otherwise existed.

Federal authorities say Crawford first contacted two Jewish groups, leading to the investigation.

Crawford faces up to 15 years in prison if convicted.

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