The letter - a request to the Port Authority that it cover Wildstein's legal fees - claims that the evidence contradicts Christie, whose administration has been embroiled in scandal since revelations three weeks ago linking a top aide and a close political adviser to an apparent plot to jam traffic in Fort Lee.
Previously, Christie said he had no reason to doubt another former Port Authority official who told lawmakers that the closures were part of a traffic study.
"Evidence exists . . . tying Mr. Christie to having knowledge of the lane closures, during the period when the lanes were closed, contrary to what the governor stated publicly in a two-hour news conference," Zegas wrote in the letter.
At that Jan. 9 news conference, Christie said he had fired a deputy chief of staff, Bridget Kelly, who was implicated in e-mails subpoenaed by state lawmakers and disclosed a day earlier. Christie also dismissed adviser Bill Stepien.
"I had no knowledge or involvement in this issue, in its planning, or its execution, and I am stunned by the abject stupidity that was shown here," Christie said at the news conference. He also said, "I first found out about it after it was over."
Other subpoenaed documents released later by lawmakers showed that some of Christie's top aides, including incoming chief of staff Regina Egea and spokesman Michael Drewniak, were sent e-mails about the closures in the week they occurred.
A statement released by Christie's office Friday said Zegas' letter did not contradict Christie.
"Mr. Wildstein's lawyer 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," the statement reads.
Wildstein, under subpoena by state lawmakers, provided the documents implicating Kelly and Stepien. He refused to testify during a legislative hearing this month. Zegas has said Wildstein will talk if granted immunity by federal prosecutors.
A lawyer for Stepien on Friday said his client was fighting a legislative subpoena for documents. In a 19-page letter, Kevin Marino told lawyers for the legislative investigatory committee that "Stepien has not broken any laws" and that the subpoena violated his Fifth Amendment rights.
Responding to Zegas' letter, Christie's office pointed to Christie's remarks last month and at a news conference Dec. 13, when the governor announced the resignation of Bill Baroni, the Port Authority appointee who said the closures were part of a traffic study.
According to Christie's office, the governor "only first learned lanes were closed when it was reported by the press and . . . had no indication that this was anything other than a traffic study until he read otherwise the morning of Jan. 8."
The Wall Street Journal reported Oct. 1 that the Port Authority's executive director, Pat Foye, had ordered the lanes reopened Sept. 13, calling the closures "abusive." A traffic columnist for the Bergen Record had also reported on the gridlock Sept. 13. Christie's office did not respond to a follow-up question Friday about which news account the governor meant.
Christie - who has not taken questions from reporters since Jan. 9 - was in New York City on Friday evening, attending radio host Howard Stern's birthday celebration. In a brief appearance onstage, he plugged New Jersey's hosting of the Super Bowl this weekend before introducing fellow New Jersey native Jon Bon Jovi, who performed "Wanted Dead or Alive."
In his letter, Zegas also wrote that Wildstein "contests the accuracy of various statements the governor made about him, and he can prove the inaccuracy of some." He did not elaborate. Christie's office said the governor "denies Mr. Wildstein's lawyer's other assertions."
The former Port Authority official - a high school classmate of Christie's, hired at the agency with the governor's approval - resigned in early December after Baroni told lawmakers that Wildstein directed the lane closures.
The documents Wildstein turned over to state lawmakers included the Aug. 13 e-mail from Kelly that said: "Time for some traffic problems in Fort Lee." Wildstein responded, "Got it." The documents do not reveal a motive but suggest the lane closures targeted the Democratic mayor of Fort Lee, who did not endorse Christie's reelection.
The lawmakers leading the probe into the closures, Assemblyman John Wisniewski (D., Middlesex) and Sen. Loretta Weinberg (D., Bergen), said in a statement Friday that they had read the letter from Zegas and "will consider it as our investigation moves forward."
Wisniewski and Weinberg said they were reviewing the letter from Marino and considering legal options to enforce Stepien's subpoena.
In addition to the legislative probe, the U.S. Attorney's Office is reviewing the closures and has issued subpoenas. Officials for Christie's reelection campaign, which received a subpoena, are seeking to use leftover campaign funds - and raise more money, if needed - to cover the legal costs.
Federal prosecutors are also apparently investigating claims that Christie officials conditioned the release of Hurricane Sandy aid on the approval of a private redevelopment deal in Hoboken.
On Friday, a spokesman for Hoboken Mayor Dawn Zimmer said the city had received a subpoena from the U.S. Attorney's Office and was complying with the request. Christie officials have denied Zimmer's claims.
Inquirer staff writer Jonathan Lai contributed to this article.