Demetrius Blackwell, seen May 3, 2015, is charged in connection...

Demetrius Blackwell, seen May 3, 2015, is charged in connection with the 2015 Queens shooting death of NYPD Officer Brian Moore of Plainedge. Credit: AP / Theodore Parisienne

A neuropsychologist on Thursday testified that the epileptic man who shot and killed an NYPD officer from Long Island in 2015 suffered from brain damage so debilitating that it caused him to fire his gun out of impulse.

Dr. Sarah Schaffer, a defense witness, told jurors in Queens Criminal Court that the defendant, Demetrius Blackwell, suffered from paranoia and spontaneously fired his gun when two plainclothes police officers stopped and questioned him on May 2, 2015.

“He wasn’t fully in control of his faculties and reacted impulsively,” Schaffer told jurors before state Supreme Court Justice Gregory Lasak.

It’s not clear why Blackwell’s court-appointed attorney, David Bart of Flushing, called Schaffer to testify about the defendant’s mental condition when one of Blackwell’s defenses is that he didn’t do it.

Blackwell, 37, is on trial on first-degree murder charges in the death of NYPD Officer Brian Moore, 25, of Plainedge, and other charges. If convicted of first-degree murder, he faces life in prison without parole. Blackwell has pleaded not guilty.

Immediately after the shooting, authorities said Blackwell fled, got rid of the gun, changed his clothes, and gave police a false name when officers canvassed the neighborhood asking residents for help locating the shooter. Blackwell was arrested about an hour and fifteen minutes after the shooting.

While cross-examining Schaffer, Queens Assistant District Attorney Robert Masters asked the neuropsychologist how it is possible that Blackwell had no self control, but had the mind to deceive authorities and attempt to hide his crime immediately after the shooting.

Schaffer said it’s possible because Blackwell’s cognitive ability was so compromised by the “hundreds” of seizures he suffered since he was a child. Some of those episodes were so severe that they sent him to the hospital.

Schaffer said she based her conclusion largely on Blackwell’s medical history, which included surgery, tests she administered and interviews with him.

Blackwell, however, never told Schaffer what happened at the time of the shooting because she said he told her he wasn’t there.

“Do you know his emotional state at the time Officer Moore was shot?” Masters asked Schaffer.

“I don’t know,” Schaffer replied.

Masters asked the neuropsychologist whether she was guessing.

“I am speculating, yes,” said Schaffer.

On Friday, the prosecution plans to call two doctors to rebut Schaffer’s testimony.

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