TRENTON, N.J. -- New Jersey lawmakers probing politically motivated traffic jams near the George Washington Bridge last year have found no evidence that Gov. Chris Christie, a possible 2016 Republican presidential contender, was involved in the scheme.

They did not rule out the possibility, however, as they have been unable to interview several witnesses.

Investigators found no conclusive evidence that Christie was aware of the lane closures, but they say that two former Christie aides acted with "perceived impunity" and with little regard for public safety when they ordered the lanes closed, according to a 136-page interim report by a joint legislative panel.

A report commissioned by Christie previously cleared him of any wrongdoing, and a lawyer for the governor said in a statement Thursday night that the report corroborates that investigation.

"The Committee has finally acknowledged what we reported nine months ago -- namely, that there is not a shred of evidence Governor Christie knew anything about the GWB lane realignment beforehand or that any current member of his staff was involved in that decision," Christie attorney Randy Mastro said in a statement.

But the report notes that important questions remain unanswered and several critical witnesses have not testified. The report will be supplemented if more information is obtained. An investigation by the U.S. attorney's office continues.

"At present, there is no conclusive evidence as to whether Governor Chris Christie was or was not aware of the lane closures either in advance of their implementation or contemporaneously as they were occurring," according to the report. "Nor is there conclusive evidence as to whether Governor Christie did or did not have involvement in implementing or directing the lane closures."

The report says former Christie aides Bridget Kelly and David Wildstein acted with "perceived impunity" and with little regard for public safety. It says the Christie administration responded "very slowly and passively" to the lane closures.

Documents released earlier this year showed that Wildstein, then an official at the Port Authority of New York and New Jersey, which operates the bridge, and Kelly, then an aide to Christie, orchestrated the shutdown, apparently as retribution toward Fort Lee's Democratic mayor. In one email, Kelly told Wildstein, "Time for some traffic problems in Fort Lee."

Wildstein later contended that Christie knew about the lane closures as they happened. Christie denies that he had any role in or knowledge of a plot to shut down the lanes. The report says the committee can't "evaluate the reliability of this evidence," after Wildstein refused to answer any questions, citing his right not to incriminate himself.