TRENTON -- Prosecutors in New Jersey are notifying more than 20,000 people charged with drunken driving that their cases are under review after a State Police sergeant who oversaw breath-testing devices was accused of falsifying records, NJ Advance Media has learned.

County prosecutors have been sending letters to people charged with driving while intoxicated between 2008 and 2016 that a specially appointed judge would weigh "whether you are entitled to relief" based on the accusations against the sergeant.

Prosecutors and defense attorneys told NJ Advance Media the number of cases that could be thrown out as a result of the criminal inquiry is likely low. But the issue, which came amid a similar probe of the State Police drug lab, created a morass of legal challenges which could take years to sort out.

Sgt. Marc Dennis, a coordinator in the State Police Alcohol Drug Testing Unit, was accused last year of lying on official documents about completing a legally required step in re-calibrating the machines, known as Alcotest devices, which are used to check the blood-alcohol level of accused drunken drivers.

The sergeant, who denies the charges against him, was allegedly observed skipping the step in calibrating just three machines. But the criminal accusations raised a cloud of doubt over every device touched by the trooper, who performed routine checks on devices used by local police across five counties.

"Sergeant Dennis' alleged false swearing and improper calibrations of these three instruments may call into question all of the calibrations performed by Sergeant Dennis over the course of his career as a coordinator," said one letter, a copy of which was obtained by NJ Advance Media.

The letters were sent in recent weeks to DWI defendants in Middlesex, Monmouth, Ocean, Somerset, and Union counties.

Dennis was charged in September 2016 with second-degree official misconduct, third-degree tampering with public records and fourth degree falsifying records. He was indicted on those same charges in December, but the misconduct charge was dropped in a second indictment in June, records show.

His attorney, Robert Ebberup, said Dennis denied any wrongdoing.

"At the end of the day, I'm sure he is going to be exonerated," Ebberup said.

In the meantime, a retired appellate judge, Joseph Lisa, is sorting through the thicket of as many as 20,667 cases affected by the claims against the sergeant.

According to an April Supreme Court order apponting him as "special master," Lisa will rule on whether Dennis' alleged failure to perform a preliminary temperature check required under Supreme Court rules would "undermine or call into question the scientific reliability of breath tests subsequently performed" on those devices.

The state Division of Criminal Justice has maintained that the check, while legally required, was not scientifically necessary.

But under state law, a person is guilty of driving under the influence if they have a blood-alcohol level of .08 percent. Tougher penalties kick in for those who blow a .10 or higher.

Defense attorneys argue that because guilt or innocence or the level of punishment can hinge on a few decimal points, anything that suggests protocols weren't followed should bring test results into doubt.

A spokesman for the state judiciary said a hearing date on the matter had not been set.

The state also faces a potential class-action lawsuit filed on behalf of those defendants. That suit, filed in federal court, was dismissed in August but could be reinstated pending the state judge's decision.

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