Looking back at former Trump fixer on the stand in hush money trial: Who is Michael Cohen?

Michael Cohen, Donald Trump's former lawyer and fixer, took the witness stand Monday in Trump's criminal hush money trial.

Cohen's testimony could be a central link prosecutors use to show Trump authorized the $130,000 paid to porn star Stormy Daniels in an attempt to stop her story about an alleged affair from becoming public ahead of the 2016 election. Trump has been charged with 34 counts of falsifying business records to allegedly disguise reimbursing Cohen.

But Cohen's journey to the witness stand has been complicated. Once an adamant Trump loyalist, Cohen has repeatedly attacked Trump in recent years. He has also been convicted of several felonies, including lying to Congress:

Here is what to know about Cohen, a key witness in Trump's criminal trial:

Trump trial live updates: Latest updates as Michael Cohen returns as hush money witness

How long did Michael Cohen work for Trump?

Cohen was Trump's personal attorney and fixer from 2006 until 2018.

How long was Michael Cohen's prison sentence?

Michael Cohen was sentenced to three years in prison. He started his sentence in May 2019, but was sent home early for house arrest due to the COVID-19 pandemic.

Where did Michael Cohen go to law school?

Michael Cohen went to Thomas M. Cooley Law School in Lansing, Michigan. Politico reported that "Cooley may be, by some measurements, the worst law school in America."

What did Michael Cohen lie about?

In November 2018, Michael Cohen pleaded guilty to one count of making false statements to Congress. In an effort to protect Trump, had told Congress his boss stopped trying to pursue a real-estate deal in Moscow in January 2016 when they actually continued efforts through June 2016.

That guilty plea came months after Cohen pleaded guilty to tax evasion, making false statements to a bank, and violating campaign finance laws by causing or issuing two hush money payments: $130,000 to Stormy Daniels and $150,00 to Karen McDougal, the latter of which was paid by American Media Inc. Those amounts greatly exceed the personal contribution limits to a political candidate.

Cohen was sentenced to three years in prison, according to a Department of Justice release.

Why did Michael Cohen turn on Trump?

Cohen's falling out with Trump was partly due to his conviction. In February 2019, he told a congressional committee he made a clean break with Trump.

"I have done bad things, but I am not a bad man. I have fixed things, but I am no longer your fixer, Mr. Trump," Cohen said in a dramatic testimony.

The two have continuously lobbed attacks at one another since then.

Contributing: Aysha Bagchi, Erin Kelly, Josh Meyer

This article originally appeared on USA TODAY: Who is Michael Cohen? The 411 about Trump's fixer who testified today