CNN–David Pecker is breaking his silence.

The former National Enquirer boss on Monday became the first witness called to testify in Donald Trump’s historic hush-money trial. Sitting in the Manhattan courtroom, Pecker offered illuminating details into how the infamous tabloid operated and conducted so-called “catch and kill” operations.

It was the first time that Pecker has spoken publicly about the secret practice — buying exclusive rights to a story for the express purpose of never publishing the information — since the tactic gained widespread notoriety during the 2016 presidential election. The Wall Street Journal, which led the way reporting on the story, first broke news in November 2016 — just days before the election — that Enquirer-parent American Media Inc. had paid former Playboy model Karen McDougal $150,000 for the rights to a story about an affair she alleged with Trump.

Pecker also allegedly alerted the Trump camp to adult film star Stormy Daniels’ decision to go public with her alleged affair with Trump, which was then captured in a $130,000 hush payment.

But while The Journal and other news outlets reported heavily on how Pecker shielded Trump from the embarrassing affair allegations by purchasing the rights to damaging stories and then never letting them see the light of day, Pecker has never spoken a word about it — until now.

The one-time Trump ally, who was granted immunity by prosecutors to testify in the case, only took the stand for a short period Monday, as court wrapped in the early afternoon. But during his brief time on the witness stand, Pecker confirmed a number of details that news organizations had previously reported about his operation.

Pecker said editors could spend upwards of $10,000 on a story, but that anything more required his explicit approval. And he said that stories of significance had to be approved by him. In other words, as then-chairman of AMI, he was read in on the stories that would have touched Trump. Given their nature, they would have certainly arrived on his desk.

As Pecker testified, Trump sat emotionless as he looked at his one-time ally divulge details about the scheme that has put him in serious legal jeopardy, the CNN team at the courthouse reported. Pecker smiled and said “hi” to Trump’s table after stepping down from the witness stand. But the former president, who finds himself forced to sit in a New York court, instead of campaigning across the country, cannot be happy with how this has all played out.

And the trial is only getting underway.

Pecker will be back on the witness stand Tuesday, when court resumes. And over the course of his testimony, he is expected to offer far more information about how the Enquirer, which boosted Trump’s candidacy in the 2016 election, protected the Republican frontrunner from the damaging stories.

While the tawdry details of tabloid journalism are sure to be put on full display, by selecting Pecker as the first witness in the case, prosecutors are clearly banking on his testimony to lay bare the conspiracy to influence the election. On the stand Monday, Pecker said he maintained two email addresses, one for general work and another private one for emails that “I didn’t want my assistant to see.”

Given his close friendship with Trump, Pecker’s private inbox of salacious tabloid secrets could hold the key to Trump’s legal fate.