Epstein paid for a conference of top scientists in 2006. His motives are now clear

The submarine ride capped a nearly weeklong gathering funded by Epstein. It brought together around 20 of the world's top physicists, including three Nobel laureates and three more who would later receive the prestigious prize.

The 2006 Virgin Islands conference illustrates how Epstein used philanthropy to build relationships with scientists and academic institutions. NPR spoke to scientists and searched through the Department of Justice documents on Epstein to understand how he built his network of prominent scientists. Epstein's interests spanned fields including theoretical physics, evolutionary biology and computer science, and he funded conferences, research programs and individual scientists

But if the idea was to keep Epstein's private life a secret, it wasn't entirely effective. There were hints.

Guth said that during the conference, Epstein "was around but was really quite inconspicuous. He did not act as a host. He acted as a bystander." However, "we probably never saw him without three or four young women," Guth said.

Scientists got money; Epstein got prestige

A number of scientists who spoke to NPR echoed that assessment — that Epstein was eager to engage on the leading science topics of the day but had only a cursory understanding of them. Still, Woit concedes that "scientists love to have somebody who is willing to talk to them."

After Epstein's arrest, he leveraged those relationships to help rehabilitate his image. In one instance, in 2012, someone (whose name is redacted) sent Epstein an email informing him that they were "rehas[h]ing an article … on the gravity conference." The following month, a press release was issued promoting the 2006 "Confronting Gravity" conference, without mentioning that it took place six years previously.

Woit said it seemed to be an effort to keep alive the notion that Epstein was still relevant in the world of science. "After 2006 … it was clear there was a large component of his activities that was reputation laundering," he said.

Krauss, on the other hand, did have a close relationship with Epstein, who donated $250,000 to his Origins Project at Arizona State. When allegations of misconduct arose against Krauss at ASU, the physicist exchanged dozens of messages and emails with Epstein seeking advice on how to handle them. "This is your life and future. I would not be cavalier as you write," Epstein wrote in a text to Krauss about how he should respond.

At the end of one conversation, Krauss said: "Thanks for everything Jeffrey."

Krauss said he never saw the other side of Epstein. "Not once in that 15 years did he ever say, 'Hey, I've got a young woman … .' He wanted to talk about other things, and he wanted to help," he said.

Krauss said Epstein reached out to him when he got out of jail in 2009. Epstein told him that the "experience had changed his view of the world, and he no longer wanted to make money."

"He just wanted to support science," Krauss said. "'Well, that's just a wonderful thing,' I thought. That's what he told me, and I believed it."