Inside the once-close relationship between Trump and his 'pit bull' lawyer Michael Cohen, who is now a key witness in Trump's criminal trial

Andres Kudacki/AP

• Michael Cohen was one of Donald Trump's closest associates for years.
• Trump's former "fixer" is now a key witness in the former president's historic criminal trial.
• "What I was doing, I was doing at the direction of and benefit of Mr. Trump," Cohen testified.

Michael Cohen was once so loyal to former President Donald Trump that he vowed "to take a bullet" for him.