The prosecution in the hush money trial against Donald Trump began testimony from their key witness Michael Cohen on Monday.

Cohen, Trump's former lawyer, will continue testimony Tuesday. He's expected to outline the timeline of Trump's alleged falsifying business records in the criminal trial.

What Happened: Cohen testified Monday and shared records that showed a $130,000 payment he made to adult film star Stormy Daniels on behalf of Trump.

Several political experts and media analysts shared with MSNBC's Rachel Maddow what Cohen's testimony meant for the case.

"This is the day that Donald Trump looked most like a criminal," Lawyer and MSNBC chief legal correspondent Ari Melber said. Since the trial started on April 22, Trump looked untrustworthy, but Monday was the day that could end up being "a very bad day for him."

"His own lawyer, who famously went to prison, very clearly provided the timeline of a proactive plan to allegedly commit a crime," Melber added.

Nicolle Wallace, former White House communications director for President George W. Bush and a senior advisor for John McCain's 2008 presidential campaign, also commented on Cohen's testimony.

"No one who's come before this jury has testified to any motive other than the campaign," Wallace said. "The real crisis, the thing that makes the Stormy Daniels payment different in addition to the crimes that were committed in the fraudulent business records, is this is the one that happens in the compressed time period."

Wallace added that no witnesses have said Trump was worried about his wife Melania finding out about affairs and that he was only worried about his political concerns.

Lawyer and political commentator Katie Phang said Cohen's testimony showed the prosecution's strength.

"You saw a well-executed plan from the Manhattan DA's office to allow the introduction of certain cell phone records, text messages, emails, bank statements, it all was the corroborating evidence that allowed Michael Cohen to stand on his own," Phang said.

Related Link: Trump Hush Money Trial Has 12 Jurors: Here Are The 7 Men, 5 Women To Decide Former President's Fate

Why It's Important: Cohen will be one of the last witnesses from the prosecution team in the multi-week trial.

His testimony to helping facilitate the hush money payments made to several parties supports allegations that Trump had approved payments to illegally influence the 2016 presidential election.

Image: Courtesy of MSNBC