Bill Gates' past relationship with disgraced financier Jeffrey Epstein has often been a hot and contentious topic of conversation.

On Tuesday, the billionaire sat down with Judy Woodruff on PBS News Hour to discuss his philanthropic work with the Bill and Melinda Gates Foundation, including vaccine equity and the climate crisis.

“I’m extremely lucky that with the help of [former wife] Melinda and the incredible generosity of Warren Buffett, we’re able to take these important causes and bring innovation to bear,” Gates said at one point during the interview. “We were funding mRNA vaccines when it was still viewed as something that would never work … I’m very lucky to be involved in this work, it’s gone way better than I’ve expected. This will be the focus for the rest of my life.”

Related: Bill Gates Talks to Anderson Cooper About Jeffrey Epstein: 'I Made a Mistake'

Towards the end of the interview, however, Woodruff swiftly changed topics and hard-hit Gates with questions about his relationship with Epstein.

It had previously been reported that Gates and Epstein would meet over the course of several years for dinners, even after Epstein had been convicted of soliciting prostitution from a minor in 2011.

“What did you know about him when you were meeting with him, as you’ve said yourself, in the hopes of raising money,” Woodruff pressed.

Gates began to fidget and avert eye contact before answering.

“I had dinners with him. I regret doing that,” the Microsoft founder said. “[Epstein] had relationships with people he said would give to global health which is an interest I have, not nearly enough philanthropy goes in that direction. You know, those meetings were a mistake, they didn’t result in what he purported and I cut them off. That goes back a long time ago now, there’s nothing new on that.”

Though it was clear that Gates did not want to speak further on the topic, Woodruff continued on, pointing out that Gates continued to meet with him for several years, and asked him what he did when he found out about his background.

“I said I regretted having those dinners, there’s absolutely nothing new on that,” Gates stated.

Woodruff asked again if Gates learned any lessons from the fallout of the Epstein situation, to which Gates replied and shut the conversation down and redirected the conversation back to the realm of philanthropic work.

“Well, he’s dead, so in general you always have to be careful,” he said, fidgeting. “I’m very proud of what we’ve done in philanthropy, very proud of the work of the foundation. That’s what I get up every day and focus on.”

This isn't the first time Gates has been pressed about his meetings with Epstein. A sit down with Anderson Cooper from August also put the billionaire in the hot seat regarding the same topic.

"It was a huge mistake to spend time with [Jeffrey Epstein], to give him the credibility of being there," Gates told Cooper at the time. "There were lots of others in that same situation, but I made a mistake.”

As of Thursday morning, Bill Gates was ranked as the fourth richest person in the world with a net worth estimate of $132 billion, according to Forbes.