At about 3 a.m., a uniformed officer with the Nassau County Police Department spotted the BMW pulled over on the side of the road, near Jericho Turnpike. The officer saw “two people outside of it,” Mr. Browne said, suggesting that it was Mr. Blake and an accomplice.

“It looks like they are swapping license plates on the vehicle,” Mr. Browne said.

The officer, from the Third Precinct, went to inquire, but the two men jumped in the car and took off westbound on Jericho Turnpike, and then southbound on the Cross Island Parkway, Mr. Browne said. The officer followed the BMW in a marked squad car but lost control on the snow-covered streets, and his car flipped over.

The officer was taken to a hospital for evaluation; a spokeswoman for the Nassau Police Department described his injuries as not life-threatening.

The BMW was next seen in Inwood at 9 a.m. on Wednesday. Witnesses, including the yellow cab driver, said that the suspect tried to drive away after the accident, but that the BMW’s undercarriage got hung up on a concrete divider as he attempted a U-turn at Dyckman Street and 10th Avenue.

When the responding officers from the 34th Precinct looked inside the BMW, they saw several .38-caliber bullets sprinkled in the car’s blood-spattered interior.

The car had only one license plate, affixed to the rear, and the officers had determined that it had been stolen from a 1999 Toyota Camry left in a parking lot in Queens.