An Oyster Bay man accused of impersonating a police officer was indicted in connection with two motor vehicle stops and a robbery, all in one day, authorities said Monday.

David Nourmand, 32, was arraigned on charges of third-degree robbery, a felony, and three misdemeanors -- two counts of second-degree criminal impersonation and second-degree unlawful imprisonment.

On May 22, he was in his BMW when he pulled over a taxi carrying passengers in Upper Brookville and demanded identification from everyone, saying "We are looking for a killer," Nassau police had said. He took off when someone in the taxi asked him to show identification, police said.

Then 10 minutes later, at 1:30 a.m., he stole a cellphone from a woman outside a Westbury hotel, police said.

At 2 p.m., he used a black sport utility vehicle to block a van driver in a travel lane of the Northern State Parkway, ordering her to get out of the vehicle and show him what was inside the van, State Police had said.

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When a passing school bus driver asked what was going on, Nourmand drove off, investigators said.

He was later arrested by Nassau police when he returned to the Westbury hotel, authorities said. The van driver saw the story of his arrest on News 12 Long Island and contacted state troopers, authorities said.

The indictment downgraded charges against the suspect from felony criminal impersonation of an officer and unlawful imprisonment to misdemeanors in the Northern State Parkway case.

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Nourmand's attorney did not immediately return a call Monday afternoon. His bail was continued at $25,000 bond or $12,500 cash.

"The defendant allegedly went on a one-man crime spree, impersonating a police officer twice in one day and senselessly robbing a woman of her cellphone," Nassau County acting District Attorney Madeline Singas said in a news release.