The investigation found that the driver, housekeeper Gloria Rosel, never braked before she crashed into a wall, Harrison police Capt. Anthony Marraccini said. She was not seriously injured.
"The vehicle accelerator in this case was depressed 100 percent at the time of collision, and there was absolutely no indication of any brake application," Marraccini said.
"She believes she depressed the brake, but that just simply isn't the case here," he said. There was no intent to deceive, Marraccini said, and Rosel won't be charged.
The finding concurs with that of U.S. safety regulators, who said last week that the car's computers showed the throttle was open and the brakes not applied.
Rosel, 56, was driving the 2005 Prius on March 9 when she reported that it sped up on its own down a driveway and slammed into a stone wall despite her braking.
Marraccini said the car's computers showed that the Prius' top speed down the driveway was 35 mph and it was going 27 mph when it hit the wall.
Toyota spokesman Wade Hoyt said the investigation showed that the company's cars are safe, and that "if you step on the brake they'll stop, even if the accelerator is glued to the floor."
The accident set off an intense investigation because Toyota has recalled more than 8 million cars since the fall over gas pedals that could become stuck or be held down by floor mats.
The Prius in the Harrison crash had not been recalled for sticky accelerators. However, it had been repaired for the floor mat problem.
Technicians from Toyota and the National Highway Traffic Safety Administration, as well as the police department's own consultants, examined the wreck outside police headquarters in Harrison on Wednesday. Marraccini said the NHTSA also interviewed the driver.
On Thursday, the NHTSA said information from the car's computer systems indicated that there was no application of the brakes and that the throttle was fully open. It did not elaborate.
The Prius is equipped with an event data recorder, or "black box," designed to record the state of the car at the moment of an impact.
The New York crash happened the day after a driver in San Diego reported that the gas pedal got stuck on his 2008 Prius, resulting in a 94 mph ride on a Southern California freeway.
Toyota said its tests showed the car's gas pedal, backup safety system and electronics were working fine.
Some consumer groups and safety experts have said the problems could be caused by faulty electronic throttles. Toyota has said it has found no evidence of problems with its electronics.
Kristen Tabar, an electronics general manager with Toyota's technical center in Ann Arbor, Mich., said in a video clip posted by the company that the automaker has eight labs in Japan that it uses to bombard vehicles with electronic interference.
She said Toyota ensures that "every system in the vehicle operates properly under those conditions."