ALBANY, N.Y. >> State regulators repeatedly failed to properly oversee a poorly maintained stretch limousine with corroded brakes that hurtled down a hill at more than 100 mph and crashed in a ravine, killing 20 people, federal investigators said Tuesday.

National Transportation Safety Board members unanimously voted to accept a final report that found widespread fault in the 2018 crash in upstate New York.

The NTSB found that the crash was likely caused by Prestige Limousine’s “egregious disregard for safety” that resulted in brake failure on a long downhill stretch of road and that ineffective state oversight contributed.

NTSB Chairperson Robert Sumwalt also criticized the local prosecutor and state police for what he said was a lack of cooperation with the agency’s crash investigation.

The crash killed 17 family members and friends, including four sisters and three of their husbands, along with the driver and two bystanders outside a country store. It was the deadliest transportation disaster in the United States in a decade.

“Seventeen young people made the smart, safe decision to arrange for sober transportation when celebrating,” board member Michael Graham said during an online hearing. “They put their trust and safety into system designed to protect them, and it failed.”

Lee Kindlon, a lawyer for Prestige operator Nauman Hussain, said his client tried to maintain the limousine and relied on what he was told by state officials and a repair shop that inspected it.

Staff members told the board that the brake system was corroded and that a brake line was crimped, which would have restricted the fluid flowing to the right rear brake. Parts of the line were coated in brake fluid, indicating a leak.

The NTSB last month released a cache of documents indicating Prestige repeatedly changed the listed number of seats in the 2001 Ford Excursion limo and took other steps to avoid safety regulations. The NTSB on Tuesday faulted the state for letting it happen.

The board said the New York Department of Transportation knew of Prestige’s out-of-service violations and lack of operating authority. The board said the state Department of Motor Vehicles failed to properly register the limousine, allowing Prestige to circumvent safety regulations and inspection requirements.

The two state agencies said they “ordered that vehicle off the road multiple times.”

The limousine had been rented to take a group of young friends and siblings to a 30th birthday celebration at a brewery near Cooperstown on Oct. 6, 2018. The vehicle’s brakes failed on a downhill stretch of a state route in Schoharie, 30 miles west of Albany. It blew through a stop sign at a T intersection and crashed shortly before 2 p.m.

Hussain faces 20 charges each of manslaughter and criminally negligent homicide. He has pleaded not guilty and was scheduled to stand trial in May, but the trial was delayed because of the pandemic. His lawyers have been meeting with prosecutors to discuss a possible plea deal.

“We have known a lot of the very granular detail of this investigation for a long time, so nothing caught us by surprise,” Kindlon said.

The NTSB documents released last month indicate Prestige took pains to avoid more stringent inspection rules intended to ensure a modified vehicle has the braking capacity and other requirements for carrying a heavier load.

When it registered the limo, it didn’t disclose to the DMV that it had been stretched, as required, and falsified the seating capacity from 18 down to 11. The company further reduced the seating capacity to 8 when it registered the vehicle in 2017, and listed the capacity as 10 in 2018, documents show.

Any vehicle with 15 or more seats is defined as a bus under state regulations and is subject to semi-annual inspections.

Thomas King, who lost four daughters in the crash, said he agreed with the NTSB that “all the parties dropped the ball.” Kevin Cushing, who lost his son, said as difficult as it was to read the NTSB report, it was good to see all the facts laid out.

“There’s certainly not any closure, by any stretch,” Cushing said. “Does it reopen wounds? I’m not sure that the wounds have closed.”

Sumwalt said a lack of cooperation from law enforcement delayed the completion of the investigation to almost two full years after the crash.

“Unfortunately, the parallel criminal investigation conducted by the Schoharie County District Attorney’s Office and the New York State Police significantly impeded and curtailed our typical investigative efforts,” Sumwalt said in his opening statement. “Particularly early in our investigation, some NTSB investigators were outright blocked from even viewing, let alone examining, critical evidence.”

State Police spokesman William Duffy said the NTSB has been “fully aware that the criminal case is the priority,” and noted that an in-court agreement was reached on January 2019 regarding NTSB’s access to the limousine.

As part of the report, the NTSB issued limousine safety recommendations to federal and state officials and to the National Limousine Association.