There have been several significant developments regarding President Donald Trump's longtime lawyer Michael Cohen in the past day.

He appears to be sending signals to the president that he's readying to cooperate with investigators.

A former prosecutor said it looked as if Cohen was "getting weak in the knees."

Michael Cohen looks to have sent President Donald Trump a lot of signals in recent days.

"He may be trying to send a message to Trump that he is prepared to cooperate unless....." the Harvard law professor Alan Dershowitz, who often speaks with Trump, told Business Insider in response to the flurry of news from the past 24 hours.

On Tuesday, Cohen, the president's longtime attorney, hired Guy Petrillo as the latest lawyer representing him the criminal investigation taking place in the Southern District of New York. Petrillo, a partner at Petrillo Klein & Boxer, has extensive experience in the district.

Cohen is under criminal investigation there on suspicion of campaign-finance violations, bank fraud, wire fraud, illegal lobbying, and possible other crimes following FBI raids on his home, office, and hotel room in April. Experts told Business Insider that Petrillo was the kind of attorney you would hire if you were looking to cut a deal in such a case.

The legal-team shake-up drove rumors that Cohen may decide to provide investigators with information on the president as a part of his cooperation with the government. Those rumors intensified with several developments.

First, The Wall Street Journal reported that Cohen had frequently told his friends in recent months that he was frustrated Trump hadn't offered to pay his legal bills. Those fees are "bankrupting" Cohen, the report said, and Cohen believes Trump owes him for his years of loyalty.

The Trump campaign had paid Cohen's legal bills as they related to the special counsel Robert Mueller's investigation of Russian interference in the 2016 presidential election. Those payments did not cover the investigation taking place in the Southern District of New York. People familiar with the payments told The Journal that Trump's family paid for part of Cohen's legal bills as they related to the strenuous document review taking place in SDNY, but the president's family did not agree to cover all of Cohen's costs.

Meanwhile, one of Cohen's New York associates told CNN that the lawyer "knows a lot of things about the president and he's not averse to talking in the right situation."

"If they want information on Trump, he’s willing to give it," the person said.

Another friend of Cohen's told the outlet that "he feels let down by him and isolated by him."

Whether Cohen ultimately decides to cooperate, a third friend said, depends on how serious any indictment is against him.

'He's getting weak in the knees'

Michael Cohen. AP Photo/Seth Wenig On Wednesday, another wrinkle emerged in the Cohen saga.

ABC News reported that Cohen resigned from his post on the Republican National Committee. And, in a letter Cohen wrote to the RNC's chairwoman, Ronna McDaniel, that was obtained by the outlet, Cohen criticized the president's much-maligned family-separation policy at the US-Mexico border in a rare rebuke of his old boss.

"As the son of a Polish holocaust survivor, the images and sounds of this family separation policy is heart wrenching," Cohen wrote. "While I strongly support measures that will secure our porous borders, children should never be used as bargaining chips."

An RNC official told Business Insider that Cohen hadn't done any work for the organization in months.

"He's getting weak in the knees," Roland Riopelle, a partner at Sercarz & Riopelle who was formerly a federal prosecutor in the Southern District, told Business Insider. "He's not going to go the distance."

Cohen is gearing up to cooperate with investigators, Riopelle said.

"That's the meaning of all this, frankly," he said, adding that Petrillo was "the person you want to be negotiating with the government over a cooperation deal."

Riopelle said it remained unclear how much of a deal Cohen could really make, especially because he has not yet met with prosecutors. A deal in SDNY will look much different from some of the deals that have been made in Mueller's investigation, he said.

"He's not going to get one count of making a false statement and cooperate against Trump — he's going to get eight counts with potential sentencing exposure of 1,000 years and we'll see where it goes from there," Riopelle said. "He'll have to snake his way out of it."

In reviewing the documents obtained by the FBI in the April raids, Cohen has "seen how bad the case is," Riopelle said.

"I think he's panicking because he knows what the lawyers have discussed with him," he said.

Prior to Cohen's latest wave of moves, Trump expressed no fears about his old attorney and the investigation facing him.

"I did nothing wrong," Trump told reporters outside the White House on Friday when asked about Cohen possibly "flipping" on him. "You have to understand, this stuff would've come out a long time ago. I did nothing wrong. I don't do anything wrong."