CHICAGO (CBS) — A former federal employee charged with shooting an Amtrak conductor in May in west suburban Naperville has been found mentally unfit to stand trial.

Dupage County Judge Daniel Guerin on Wednesday ruled that 79-year-old Edward Klein was “unfit to stand trial and not likely to be restored to fitness within one year,” according to DuPage County state’s attorney’s office spokesman Paul Darrah.

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Edward Klein (Credit: DuPage County sheriff’s office)

A court-ordered mental health evaluation found that Klein suffered from impaired cognitive disorder and dementia.

Klein, who had lived in an assisted-living facility in West Allis, Wisconsin, is next scheduled to appear in court for a status hearing Nov. 7, followed by another hearing Dec. 18, Darrah said. He could face commitment to a state mental health facility.

Klein was aboard an Amtrak train that left Kansas City for Chicago about 9 a.m. on May 16, prosecutors said. The train stopped at the downtown Naperville station about 4:45 p.m. and some passengers got off.

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Klein stayed on the train, but decided he wanted to get off after the doors closed. When he was not allowed to exit, he “pulled a revolver, stuck his arm out of the window of the train door and fired one shot, striking the victim in the abdomen,” a statement from prosecutors said.

He then tried to get off the train by climbing through the same window, but “was unable to as train personnel and other passengers detained him until authorities arrived.

Klein was charged with attempted murder and aggravated battery with a firearm, prosecutors said. He has been held on a $1.5 million bond since his arrest.

Klein formerly worked for the Federal Protective Services, a branch of Homeland Security that provides security for federal facilities, authorities said.

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(Source: Sun-Times Media Wire © Chicago Sun-Times 2016. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed.)