TRENTON -- After State Police Detective Sgt. William Billingham smashed his unmarked car into an SUV on a state highway in Camden County in 2009, he told his fellow troopers he fell asleep at the wheel.

They never tested him for alcohol and took down a fake name from the detective's undercover ID on police reports, keeping the other driver in the dark.

An internal investigation later found Billingham had a blood-alcohol level three times the legal limit. When the scandal became public, it sparked a crackdown on DWI investigations involving troopers and a big, taxpayer-funded lawsuit settlement.



But records obtained by NJ Advance Media show that, years after the story receded from the spotlight, the trooper struck a court deal in December allowing him to avoid jail time -- or even a guilty plea -- and is now seeking a disability pension.



Billingham was the subject of a 2011 Star-Ledger investigation which found the victim of the crash, Clayton Tanksley, spent the months afterward chasing a ghost, filing insurance claims and hiring a private investigator to find a man who didn't exist.



Paperwork given to Tanksley and his insurer named the driver as William Gillespie, a pseudonym the trooper used for undercover work, the investigation found.



The state eventually paid Tanksley $150,000 in a civil settlement. The criminal case against Billingham, who was off-duty but driving a state vehicle, stretched on for years.



State Police launched an investigation three months after the crash when the Attorney General's Office received an anonymous letter claiming the trooper's intoxication was covered up.



He was indicted in July 2011 on a fourth-degree charge of assault by auto, in part because the statute of limitations for DWI had long passed.

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The detective fought in court to suppress hospital records showing his blood-alcohol level was 0.276, but an appellate court ruled in 2012 the medical records were fair game.



It's unclear why the case continued for years after that. Records show Billingham applied for pretrial intervention as early as April 2013, a month after the state Supreme Court declined to take up the hospital records dispute.

But the agreement was not signed by a judge or prosecutor until just last December.

Under pretrial intervention, also known as PTI, a defendant with little or no criminal history can apply to have their case put on hold for one to three years while they are subject to a range of conditions including random urine testing, psychological or substance abuse treatment and community service. If they follow the rules, the charges are dropped.

A copy of the trooper's order of postponement obtained by NJ Advance Media shows charges against Billingham will be dropped in December of this year if he meets the conditions of "supervisory treatment."

The Ocean County Prosecutor's Office, which took over the case because Billingham's brother was Camden County sheriff at the time, signed off on the deferment. A spokesman for that office declined to comment.

The PTI agreement marked a quiet end for a controversy that made headlines and prompted major policy changes within the State Police.

Days after Billingham's case became public, Col. Rick Fuentes ordered stricter oversight of DWI investigations involving troopers and launched a review on the use of undercover identification cards like the one Billingham gave to troopers on the scene.

However, the suspended criminal matter still complicates the detective's application with the State Police retirement board, which has to determine whether Billingham meets the state's "honorable service" requirement for pensions.

The trooper's request for an accidental disability retirement appears unrelated to the off-duty drunken driving incident.

According to a heavily redacted copy of Billingham's pension documents obtained by NJ Advance Media through a public records request, the detective cites two incidents as the cause of his undisclosed injury, one on January 26, 2010 and another on October 6, 2009 -- just six months after the crash.

The details of those incidents aren't subject to release under medical privacy provisions in New Jersey's records laws.

Billingham referred a request for comment to his attorney, who declined to answer questions about the criminal matter and his accidental disability retirement application.

Billingham was scheduled to go before the board on March 28, but the matter was tabled pending further review. Treasury listings show the board directed the state Attorney General's Office to subpoena investigative records from county prosecutors.

A spokesman for Attorney General Christopher Porrino declined to comment on the matter.

Billingham was suspended without pay after his indictment, but it's unclear whether he was ever disciplined over the crash because details of internal investigations are also often shielded from public view.

A State Police spokesman, Sgt. Jeff Flynn, said only that Billingham retired "as a result of reaching our mandatory age of retirement" and was "not involved in any pending internal investigations."

Billingham remained on the State Police payroll until 2014, when he reached the retirement age of 55 and first applied for a disability pension, records show. But he had not received his full $91,000 salary since 2010, and the last time he received any money from the State Police was 2011, the year prosecutors brought criminal charges, when he was paid $19,252.

The next State Police retirement board meeting is scheduled for May 23. A spokesman for the Treasury Department said the agenda had not been set.

S.P. Sullivan may be reached at ssullivan@njadvancemedia.com. Follow him on Twitter. Find NJ.com on Facebook.