TRENTON - One of the lawyers at the firm hired by Gov. Christie to conduct an internal investigation into the George Washington Bridge lane-closure scandal is now cohosting a fund-raising event for his presidential campaign.

The firm, Gibson, Dunn & Crutcher, continues to represent the governor's office and had billed nearly $8 million through May. That's being funded by taxpayers.

Attorney Debra Wong Yang, a partner at Gibson Dunn's Los Angeles office, is cohosting a reception for the governor at the Los Angeles home of the hedge-fund executive Steven A. Cohen, according to an invitation obtained by the Hollywood Reporter.

Tickets for Wednesday's reception cost $2,700 per person or $5,400 per couple.

Yang is a longtime friend of Christie's; their families have vacationed together. Both were appointed U.S. attorneys by President George W. Bush. Yang served in Los Angeles and Christie in New Jersey.

When Christie was a federal prosecutor, he appointed Yang to monitor a compliance settlement with an orthopedic manufacturing company, an arrangement that included a contract with the company.

It wasn't clear if Yang was still part of the Gibson Dunn team working for the governor's office. Federal prosecutors have charged three former Christie allies in the bridge incident, alleging that they conspired to cause massive traffic jams for four days in September 2013 to exact revenge against a local mayor who didn't endorse Christie's reelection campaign that year.

One of them, former Port Authority official David Wildstein, has pleaded guilty and is cooperating with the government. Bridget Anne Kelly, Christie's former deputy chief of staff, and Bill Baroni, Christie's former top appointee at the Port Authority of New York and New Jersey, have pleaded not guilty.

They have alleged in court documents that Christie's office has withheld or redacted thousands of documents that could help their defense. Christie says that's nonsense.

In March 2014, Gibson Dunn released a report that concluded Christie had no involvement in the lane closures.

Yang did not respond to a request for comment Thursday. Her involvement in the fund-raising event was first reported by WNYC.

Christie's office referred to a statement Gibson Dunn attorney Randy Mastro issued last year with regard to Yang's involvement in the investigation.

The statement said Mastro personally interviewed Christie but added that Yang attended the session, along with another attorney.

"And we had only one incentive here - to get to the truth," Mastro said. "In our search for the truth, the governor made himself available without counsel to be questioned for as long and as often as we requested. And we will ultimately be judged by whether we got it right. In fact, we had to work even harder to get it right because there are other investigations continuing out there. And on the most important questions, including that the governor knew nothing about this lane realignment beforehand, we are confident we got it right."

A spokeswoman for Christie's campaign pointed to the same statement and added that Yang's fund-raising was "not illegal or inappropriate, as this is a federal campaign."

aseidman@phillynews.com 856-779-3846 @AndrewSeidman

Inquirer staff writer Maddie Hanna contributed to this article.