WATCH: Barbara McQuade explains how she jailed mayor of Detroit -- for same thing Trump did
Donald Trump speaks on The White House lawn (MSNBC/screen grab)

On Thursday, it was revealed that a whistleblower in the intelligence community has submitted a complaint about President Donald Trump's conduct with a foreign leader.

There was widespread speculation Friday on the nature of the complaint, but experts suspect it has to do with the president trying to extract opposition research on Joe Biden from the president of Ukraine. Recently, Trump's lawyer and friend Rudy Giulani traveled to the country to unearth dirt on Biden's son.

And experts are concerned that Trump promised the foreign leader a better relationship with the U.S. in exchange.

On MSNBC Friday, former prosecutor Barbara McQuade pointed out that if Trump did that, it's tantamount to extortion—and she's helped put people in prison for far less.

"There’s certainly things he could have said that would have been highly inappropriate, if not illegal," said McQuade about Trump's conversation with the president of Ukraine.

"For example, I don’t know what the facts are here, but all of the words I’m hearing sound very consistent with an extortion demand," McQuade continued.

"When you withhold something that you have in your official power the ability to give in exchange for a thing of value to yourself, that is a classic case of extortion," she added.

"We prosecuted cases like that in my own office involving the former Mayor of the city of Detroit who withheld public works contracts until the contractors agreed to pay kickbacks to members of his association and his office. And so there are a lot of parallels there," McQuade said.

"If that’s what President Trump is doing, withholding this military aid unless and until Ukraine agrees to perform this investigation and president Biden, that would be extortion," she said.

"We all know a president cannot be indicted, but I think it could be very much an impeachable offense if those facts were to turn up to be true. What he said very much matters."