Michael Cohen, once a fierce ally to former President Donald Trump, is expected to testify at Trump’s hush money trial on Monday. Billed as a “star witness” for the Manhattan district attorney’s office, Cohen’s name has come up repeatedly since witness testimony in the trial began on April 22.

Here’s what you need to know ahead of his highly anticipated testimony.

❓What was his relationship to Trump?

Cohen worked for the Trump Organization for more than a decade as Trump’s attorney, starting in 2006. During that time, he became known as Trump’s “fixer” due to his role in covering up Trump’s problems.

Cohen was first introduced to Trump in 2006 by Donald Trump Jr. After consulting with the real estate mogul on a few legal matters, Cohen quickly became executive vice president of the Trump Organization and special counsel to Trump. As he explained to Vanity Fair in 2017, he was so devoted to Trump at the time that he said he “would take a bullet” for him.

💸 What’s Cohen’s role in the hush money trial?

Cohen said that shortly before the 2016 presidential election, he made a $130,000 payment to adult film star Stormy Daniels as she was shopping her story to major media outlets about an alleged affair she had with Trump in 2006. He said the payment was intended to silence Daniels and prevent her from speaking to the media and compromising Trump’s presidential future.

According to Cohen, Trump reimbursed him for the payment after he became president through a shell company that Cohen had opened for that sole purpose. Prosecutors claim that Trump falsified the paperwork of those payments by masking them as legal services. The paper trail of those payments make up the 34 alleged falsified records that Trump is charged with.