President Donald Trump and Rudy Giuliani's recent spate of attacks against Michael Cohen ahead of his congressional testimony prompted Justice Department veterans to suggest they may face legal exposure for attempted witness tampering.

Cohen announced that he had indefinitely postponed his congressional testimony in the wake of "ongoing threats" against his family from Trump and Giuliani.

Both men suggested that if Cohen testifies before Congress, prosecutors should investigate his father-in-law.

One criminal-law expert told INSIDER that their comments represent "a classic form of obstruction of justice and typically the FBI, and the Justice Department, takes that very seriously. If Trump were a private citizen, instead of in office, he would already be indicted for what he has said about Cohen."

Another Justice Department veteran told INSIDER that their comments may not rise to the level of a criminal witness-tampering charge.

Even so, "any prosecutor or agent working gang or organized crime cases for a few years has heard people trying to coerce and threaten witnesses to not testify. It is usually done behind closed doors with only a wiretap as the proof. Nobody has ever seen the threat blasted to 50 million Twitter followers," that DOJ veteran said.

Legal scholars and Justice Department veterans say that President Donald Trump and his lawyer, Rudy Giuliani, may have opened themselves up to a witness-tampering charge after a recent spate of attacks the two men made against Michael Cohen, Trump's former lawyer who was set to testify against Trump before Congress in February.

This week, Cohen indefinitely postponed his testimony, citing "ongoing threats against his family from President Trump" and Giuliani.

Early Thursday, Trump responded to the news in a tweet: "So interesting that bad lawyer Michael Cohen, who sadly will not be testifying before Congress, is using the lawyer of Crooked Hillary Clinton to represent him - Gee, how did that happen? Remember July 4th weekend when Crooked went before FBI & wasn’t sworn in, no tape, nothing?"

Cohen pleaded guilty to one count of lying to Congress as part of the Russia investigation last year. In a charging document, Cohen said he misled lawmakers on the House Intelligence Committee about the now defunct Trump Tower Moscow project when he testified before the panel in 2017.

Last summer, Cohen also pleaded guilty to tax evasion, bank fraud, and campaign-finance violations as part of a separate federal investigation into his and Trump's business dealings before the 2016 election.

Since he began cooperating, Cohen has implicated the president in several crimes. After Cohen's lawyer confirmed he would be appearing before the panel, Trump took to Twitter and the media to slam his former lawyer and suggest his family members should be prosecuted — an action many legal experts said rose to the level of criminal conduct on Trump's part.

Read more: Michael Cohen has reportedly been subpoenaed to testify before the Senate Intelligence Committee

Michael Cohen and President Donald Trump. Jonathan Ernst/Reuters

'You'll find out, and you'll look into it'

On Friday, Trump tweeted that Cohen is "lying to reduce his jail time" and made a vague reference to Cohen's father-in-law. "Watch father-in-law," Trump said. He echoed the claim in an interview with Fox News commentator Jeanine Pirro.

"In order to get his sentence reduced, he says, 'I have an idea. I'll tell — I'll give you some information on the president,'" Trump told Pirro. "Well, there is no information. But he should give information maybe on his father-in-law, because that's the one that people want to look at ... And I guess he didn't want to talk about his father-in-law."

Asked to identify who Cohen's father-in-law is, Trump replied, "I don't know, but you'll find out, and you'll look into it. Because nobody knows what's going on over there."

Giuliani made a similar claim last Sunday, telling CNN that Cohen's father-in-law "may have ties to something called organized crime."

When he was pressed on his comments about Cohen's father-in-law, Giuliani said they were justified.

"So, it's OK to go after the father-in-law?" CNN host Jake Tapper asked Giuliani.

"Now — now, of course it is, if the father-in-law is a criminal," Giuliani replied.

But Mimi Rocah, a former federal prosecutor from the Southern District of New York, struck down the former New York City mayor's claims.

"Nope," she wrote. "There's no 'if he’s a criminal' exception to the witness tampering statute."

Read more: What is Rudy Giuliani thinking?

Former Mayor of New York Rudolph Giuliani during the Conference In Support Of Freedom and Democracy In Iran on June 30, 2018 in Paris, France. The speakers declared their support for the Iranian peoples uprising and the democratic alternative, the National Council of Resistance of Iran and called on the international community to adopt a firm policy against the mullahs regime and stand by the arisen people of Iran. (Photo by Anthony Devlin/Getty Images)

'If Trump were a private citizen ... he would already be indicted'

Jens David Ohlin, a vice dean at Cornell Law School who is an expert on criminal law, said Trump and Giuliani's comments are "definitely witness tampering."

"Trump has suggested that if Cohen testifies, his family could be prosecuted," Ohlin told INSIDER. "That's a classic form of obstruction of justice and typically the FBI, and the Justice Department, takes that very seriously. If Trump were a private citizen, instead of in office, he would already be indicted for what he has said about Cohen."

Joyce Vance, a former federal prosecutor who spent 25 years at the Justice Department, echoed that view and told MSNBC that "using intimidation, or even attempting to use intimidation – not just to keep somebody from testifying, but even to delay them – could constitute the crime of witness tampering."

Reps. Elijah Cummings and Adam Schiff, the chairmen of the House Oversight and House Intelligence committees, respectively, released a joint statement condemning Trump and Giuliani's comments as being "mob tactics" that violate the law.

"The President should make no statement or take any action to obstruct Congress' independent oversight and investigative efforts, including by seeking to discourage any witness from testifying in response to a duly authorized request from Congress," they said.

Jeff Cramer, a former federal prosecutor in Chicago who spent 12 years at the Justice Department, told INSIDER that while Trump's comments were "clearly meant to dissuade Cohen from testifying," they don't rise to the level of a criminal charge.

But Cramer didn't mince words when discussing the gravity of Trump's comments.

"Any prosecutor or agent working gang or organized crime cases for a few years has heard people trying to coerce and threaten witnesses to not testify," he said. "It is usually done behind closed doors with only a wiretap as the proof. Nobody has ever seen the threat blasted to 50 million Twitter followers."