At the same time, Renna portrayed Kelly - whom she described as once a close friend - as an anxious and insecure manager who relied on others to make decisions.
And when it came to the September lane closures, "I wouldn't say she was the architect," Renna said.
Asked whether she believed Kelly and former Port Authority of New York and New Jersey official David Wildstein were the lone participants in plotting the closures - lawyers hired by Christie said they found no evidence anyone else was involved - Renna said, "I don't know."
Whether Kelly, who authored the infamous "Time for some traffic problems in Fort Lee" e-mail, got her orders from elsewhere was a question left unresolved Tuesday, as was the reason why two lanes from Fort Lee were closed to the bridge for four days in September, creating massive gridlock in the town.
Some have speculated the closures were retaliation against Mayor Mark Sokolich, a Democrat who did not endorse Christie's reelection.
Gibson, Dunn & Crutcher, the New York law firm Christie hired to review the lane closures, portrayed Kelly and Wildstein - who resigned from the Port Authority in December - as rogue operatives with unknown motives in a report that it said cleared the governor of wrongdoing.
Gibson Dunn's bills to the state have topped $1 million through January, according to a redacted invoice released Tuesday by the state Attorney General's Office. The firm billed the state at $350 an hour rather than a previously agreed-upon $650 an hour.
By the end of February, the legislative panel had incurred about $500,000 in legal fees, according to invoices.
Despite Gibson Dunn's findings, Renna's testimony "strongly suggests that report does not fully answer the question as to why and who . . . was involved," Assemblyman John S. Wisniewski (D., Middlesex), cochair of the legislative panel, said after Tuesday's hearing.
Renna, who resigned from Christie's administration in January, weeks after Kelly's apparent involvement was revealed, was the first in a series of witnesses expected to come before the panel in coming weeks.
Her testimony, which spanned more than five hours, echoed some of the Gibson Dunn report's portrayal of Kelly as erratic and anxious in her role as deputy chief of staff for the Office of Legislative and Intergovernmental Affairs (IGA). Renna worked under Kelly as director of IGA.
When Renna sent Kelly an e-mail with a five-paragraph description of an angry phone call staffer Evan Ridley had received from Sokolich during the lane closures - including speculation mentioned by Sokolich that the closures were a form of political retribution - Kelly replied with one word: "Good."
That type of response "was not out of the ordinary for Kelly," said Renna, who said she did not know what Kelly meant by the answer.
A month earlier, after Kelly had expressed anger to Renna about a meeting Ridley had with Sokolich, Renna told Ridley not to contact the mayor again. She said she never followed up with Kelly on the issue.
Information in the office "flowed down," Renna said. "Bridget could sometimes be a little difficult as far as sharing information goes. I never wanted her to get the feeling I was trying to overstep. . . . She shared information I needed to know, and I left it at that."
As news outlets reported on the bridge controversy in the fall, Renna said she did not suspect that Kelly had played a role in the lane closures, though she said she believed Kelly was close with Wildstein.
She said she still did not believe Kelly was involved in December, when Renna said Kelly called her after being questioned by Christie chief of staff Kevin O'Dowd about the lane closures. Describing Kelly as "enormously nervous," Renna said Kelly asked her to delete the e-mail in which she had responded with "Good."
Renna said the request seemed strange. She said she did delete the e-mail, but only after forwarding a copy to another e-mail account.
Democrats pressed Renna on why she did not tell anyone else about Kelly's request in December - a month before Kelly's "traffic problems in Fort Lee" e-mail was made public.
Renna said she thought Kelly "was just being paranoid."
She also believed that if she went to Christie's counsel, Kelly would learn of it and she would lose her job, she said. "I was fearful," Renna said.
Kelly's lawyer, Michael Critchley, said in a statement that Renna's "attempt to pile on and portray Ms. Kelly as insecure, erratic, and paranoid is completely at odds with Ms. Kelly's 20-year record serving in state government."
He said some of Renna's answers were "erroneous," but did not elaborate.
Wisniewski said after the hearing that Renna's testimony suggested "a government run by intimidation."
Renna's testimony also spurred questions from lawmakers on the line between government and campaign work in the IGA office, where some staffers tasked with assisting local elected officials also worked to secure endorsements from those officials for Christie's reelection.
Renna defended the office's work, describing it as "amazingly nonpartisan" and insisting that all campaign work was done on personal time.
According to a summary of Renna's interview with Gibson Dunn lawyers - who interviewed 75 people, but not Kelly, Wildstein, or Bill Stepien, a former IGA employee and a top Christie aide - Renna said IGA staffers received "mandatory directives," in the firm's words, not to return calls to certain mayors.
Renna said Tuesday the firm's summary was inaccurate, calling the phrase mandatory directives "aggressive language, and not language I would use."
She also said there was no list of "hands-off" mayors - mentioned by another staffer in a text message. That was "conversational" phrasing, she said.
Kelly and Stepien, backed by a court ruling, have refused to cooperate with the legislative panel's inquiry. Wildstein provided documents to the panel, but declined to answer questions.
Partisan rifts on the legislative panel were on full display Tuesday as Democrats rejected requests by the minority Republicans, who have complained of being shut out of decision-making.
Sen. Kevin O'Toole (R., Passaic) called for a special prosecutor to investigate whether panel members had leaked information to the media - an idea Paul D. Moriarty (D., Gloucester) dismissed as "preposterous."
Christie's office announced Tuesday with Democratic New York Gov. Andrew Cuomo that a bistate panel would be formed to evaluate changes at the Port Authority. The panel's creation was recommended by the Gibson Dunn report.