A Princeton graduate with a history of mental illness was convicted Friday of fatally shooting his father.

Thomas Gilbert Jr., 34, was found guilty by a Manhattan jury of killing 70-year-old Thomas Gilbert Sr., inside the family’s Beekman Place apartment on Jan. 4, 2015.

During the month-long trial, Gilbert’s defense attorneys argued that their client was insane and didn’t know the murder was wrong.

Prosecutors argued the son was enraged over the father’s cut in his allowance.

Gilbert had no visible reaction as the verdict was read by the foreman. He kept his head down and did not look at the jurors as they were dismissed from the room.

He faces life in prison.

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