A former official at the center of the traffic scandal that has ensnared New Jersey Gov. Chris Christie said Friday that there’s evidence Christie knew lanes had been closed on a bridge at the time, contradicting Christie’s insistence otherwise and reigniting a scandal that has threatened his political future.

A lawyer for David Wildstein, a top appointee at the Port Authority of New York and New Jersey and longtime Christie friend, said in a letter to the agency that “evidence exists tying Christie to knowledge” of lane closures on the George Washington Bridge “during the period when the lanes were closed, contrary to what the governor stated publicly.” The letter also said Wildstein “contests the accuracy of various statements” Christie made about Wildstein and that he “can prove the inaccuracy of some.” Wildstein did not say that he personally has evidence of Christie’s prior knowledge of the lane closures, nor did he detail what that evidence is.

The letter from Wildstein’s lawyer was sent in an effort to get the Port Authority to pay legal fees incurred by an ongoing investigation into the scandal. It is the most serious allegation to date that Christie himself knew lanes had been closed at the time of a traffic jam that snarled a north Jersey town for days last year. Documents disclosed earlier this month revealed the lane closures on the busiest bridge in the world were orchestrated by aides as apparent political payback for the town’s mayor not endorsing Christie’s reelection bid. Christie has apologized, fired a top aide involved and denied any knowledge of a political retribution scheme. But he has also said he didn’t know the lanes were closed until after the September incident, and was only told then that it was for a traffic study.

“I don’t know what else to say except to tell them that I had no knowledge of this—of the planning, the execution or anything about it—and that I first found out about it after it was over,” Christie said on Jan. 9.

Christie’s office said Friday in a statement that the letter actually “confirms what the Governor has said all along—he had absolutely no prior knowledge of the lane closures before they happened and whatever Mr. Wildstein’s motivations were for closing them to begin with.

“As the Governor said in a December 13th press conference, he only first learned lanes were closed when it was reported by the press and as he said in his January 9th press conference, had no indication that this was anything other than a traffic study until he read otherwise the morning of January 8th,” the statement read. “The Governor denies Mr. Wildstein’s lawyer’s other assertions.”

The leader of a panel of state lawmakers investigating the matter did not immediately comment. Federal authorities have also been probing the matter.

Wildstein resigned in December amid early suggestions that the lane closures were politically motivated. Testifying under subpoena before a state legislative committee earlier this month, Wildstein refused to answer questions, citing his Fifth Amendment rights to stay silent.

Fort Lee Mayor Mark Sokolich, whose town was turned into a veritable parking lot for days after dedicated lanes to the bridge were closed, responded cautiously to the news Friday.

“They’re only allegations, and I think it’s now as important as ever for the fact-finders to determine who knew what and when,” Sokolich told TIME. “With all due respect, Mr. Wildstein’s overtures don’t hit the height of my credibility scale. … I take them with a grain of salt, but it is of concern.

“I’m not rooting for anyone’s demise,” he added. “I’m rooting for the truth.”

If Wildstein’s allegations prove true, it could be a severe political blow for Christie, seen as a leading Republican presidential candidate in 2016. When the scandal broke open earlier this month, many Republican operatives credited Christie with stanching the bleeding by axing aides and denying culpability, but said evidence that Christie knew more than he let on could prove politically fatal.

-with reporting by Zeke J Miller and Andrew Katz

Write to Noah Rayman at noah.rayman@time.com and Charlotte Alter at charlotte.alter@time.com.