'Chilling' testimony promised from Trump's former lawyer

Donald Trump's former lawyer Michael Cohen could stir fresh turmoil for his former boss when he begins three days of testimony before lawmakers Tuesday on the president's murky business and personal affairs.

Already facing a three-year prison term for "dirty deeds" he performed at Trump's beckoning, Cohen will face questioning behind closed doors Tuesday at the Senate Intelligence Committee on his work for Trump and the 2016 Trump campaign's ties to Russia -- still a focus of Special Counsel Robert Mueller's investigation.

On Wednesday he will appear in public before the House Oversight Committee, and then Thursday will be quizzed in a closed hearing of the House Intelligence Committee.

"Michael Cohen is the one person who has accused the president of committing a crime," Elijah Cummings, Democratic chairman of the House Oversight Committee, told NPR.

In deference to the Mueller probe, Cummings's panel will not ask Cohen about Russia-related matters.

"The president has basically called Michael Cohen a liar. So I think it's only fair to Michael Cohen and to the president that representatives of the people... have an opportunity to ask questions," Cummings said.

According to Cummings, the committee will be probing Trump's finances -- including suspect loans from Deutsche Bank -- hush payments Trump allegedly told Cohen to arrange for two alleged former lovers, his business conflicts of interests while in politics and the practices of the Trump Organization, the billionaire president's real estate and entertainment company.

Should Cohen be candid, the testimony could be explosive.

His dozen years as a trusted Trump lieutenant gave him access to highly sensitive details of the former real estate magnate's business and personal affairs.

Cohen's lawyer Lanny Davis told ABC News that his client would detail "personal, front-line experiences" of incidents and conduct by Trump that even hardened listeners would find "chilling."