A judge will let a drunken-driving defendant withdraw her guilty plea after he found the Nassau County district attorney's office failed to disclose beforehand that an instrument that measured her breath alcohol content was contaminated.

Nassau District Court Judge Colin O'Donnell said in a July 24 decision that it was clear prosecutors and police knew about the contamination issue before defendant Jonna Kull's plea, but prosecutors notified the defense about six months later.

"Naturally, we agree with the judge's decision," said Kull's attorney, David Mirsky of Mineola.

Kull, 26, of West Hempstead, will have the chance on Sept. 12, to withdraw her June 2013 plea that had included a "no jail" commitment and be scheduled for trial.

But Paul Leonard, a spokesman for Nassau County District Attorney Kathleen Rice, said Thursday her office "disagrees with the judge's characterizations in this case and is considering our options regarding the court's ruling."

He said prosecutors didn't know about a problem with the Intoxilyzer until months after Kull's plea. The spokesman said police made Rice's office aware in October 2013 when a prosecutor requested documents in another case and learned of a work order that detailed issues with the machine. Leonard said prosecutors then started notifying attorneys for defendants with pending cases where that device was involved. He couldn't say Thursday how many cases that was or their outcomes.

Court records show police arrested Kull on Hempstead Turnpike in Franklin Square in October 2012, and charged her with misdemeanor driving while intoxicated and making an unsafe lane change -- an infraction. Records also show authorities found that a test at the scene and a breath test later at police headquarters -- with the machine in question -- showed Kull had a .14 percent breath alcohol content.

On Dec. 5, 2013, a prosecutor's letter notified Kull's lawyer that it had come to the attention of the district attorney's office that a contaminant was found on an Intoxilyzer 5000 EN machine during routine maintenance. The letter said the prosecution was working to learn whether the contaminant could have affected Kull's breath test results.

The prosecution later argued in a May 2014 motion opposing the defense's attempt to have Kull's plea tossed that while the manufacturer found contamination on the instrument, it "had no effect on the defendant's breath test."

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But O'Donnell disagreed with the prosecution's claim that testing by the manufacturer showed there was no reason to believe the instrument wasn't operating properly despite contamination.

The judge's decision also said it was uncontested that police had requested a "service work order" for the machine about six weeks before Kull's guilty plea and it showed contamination.

"This court has difficulty following the reasoning and analysis of the people," O'Donnell wrote.