Thousands of pages of new evidence and sworn testimony released on Monday show the extent to which former Gov. Andrew M. Cuomo relied on a group of allies, including his younger brother, the CNN host Chris Cuomo, to strategize how to deflect and survive a cascade of sexual harassment charges that eventually engulfed him.

Beginning last December with the first public accusation by a former aide, Lindsey Boylan, the records lay out in unvarnished detail how the tight-knit group of advisers discussed a series of increasingly drastic steps to manipulate the press, discredit his accusers and retain a grip on power that became less and less tenable.

After debating the legality of the move, they agreed to pass Ms. Boylan’s personnel file to reporters, portraying her as politically motivated and unhinged. They sought — and failed — to rally dozens of former female aides to pen an op-ed defending him.

And Chris Cuomo pressed to take on a greater role in crafting his brother’s defense, including phoning into strategy calls. At one point, he even ran down a secondhand tip that another woman accusing the governor of unwanted advances at a wedding was lying. (She was not.)

The previously unseen materials, including video of the former governor answering questions under oath, were produced earlier this year by investigators working for Letitia James, New York’s attorney general, and undergirded the damning report she released in August that ultimately led to Andrew Cuomo’s resignation.

Ms. James had already released transcripts of an 11-hour interview with Mr. Cuomo and interviews with 10 women who had accused him of a range of misconduct.

Neither Mr. Cuomo nor his spokesman immediately commented on the release.

The newly released records included copies of text and email messages, as well as transcripts of depositions with many of Mr. Cuomo’s closest aides, including Melissa DeRosa, the governor’s secretary; as well as current and former legal counselors including Steven M. Cohen, Alphonso David and Jill DesRosiers.

When the governor’s fate was first thrown into doubt earlier this year amid mounting accusations, many of them assembled in person at the Executive Mansion in Albany for a de facto war council despite the raging pandemic, Linda Lacewell, a former top aide, told investigators. Many of the attendees, including the pollster Jefrey Pollack and the political consultant Lis Smith, ended up staying overnight.

“I think as part of the human condition when you — when you feel like you’re in battle you turn to those you trust,” Richard Azzopardi, the governor’s top spokesman, told investigators.

One of the people was clearly Chris Cuomo, who appears to have played a larger role than he has admitted to or has been previously known.

“As the situation started to accelerate, my brother asked me to be in the loop,” Chris Cuomo told investigators in a six-hour interview last July. He said he saw himself as a “satellite” of his brother’s more formal advisers.

Chris Cuomo insisted to investigators that he had never manipulated coverage or spun other journalists to benefit his brother. And he has told viewers of his show that he acted only as a brother to be a sounding board “to listen and to offer my take,” advising him to tell the truth, whatever it was, and eventually to resign.

But as a working journalist with a vast network of sources in and outside of media, text messages, emails and testimony collected by investigators show Mr. Cuomo proved to be more valuable than just that to those trying to help the governor cling to power. He also argued strenuously against his brother resigning before a full investigation was conducted.

For example, when Ms. DeRosa was trying to keep tabs in early March on journalists working to uncover stories of harassment, she turned to Chris Cuomo for intelligence.

“On it,” Mr. Cuomo wrote back after one such request. A few days later, Ms. DeRosa wrote to the governor’s brother that she had heard Ronan Farrow of The New Yorker was “getting ready to move” a story. “Can u check your sources?”

CNN did not immediately respond to a request for comment.

In text messages with Ms. DeRosa in March, Mr. Cuomo said he was in a “panic” about how the governor’s team was handling the accusations and pleaded to “let me help with the prep” before drafting his own proposed statements for the governor to read.

He pleaded with Ms. DeRosa to “trust me” and outside advisers like Ms. Smith and Mr. Pollack, and to “stop hiding” details from him.

“We are making mistakes we can’t afford,” Mr. Cuomo wrote at one point.

And he used his contacts to try to aid the defense in other ways. After The New York Times reported in early March that the governor had made an unwanted advance on a young woman at a wedding, Chris Cuomo had texted Ms. DeRosa to say, “I have a lead on the wedding girl,” who he believed had been acting maliciously to damage the governor.

The lead turned out to be bunk, he told investigators.

John Koblin contributed reporting.