WikiLeaks and its founder, Julian Assange, are facing multiple investigations by U.S. authorities, including three congressional probes and a federal criminal inquiry, sources familiar with the investigations said.

The Senate and House of Representatives intelligence committees and leaders of the Senate Judiciary Committee are probing the website's role in the 2016 U.S. presidential election campaign, according to the sources, who all requested anonymity, and public documents.

WikiLeaks published emails hacked from the Democratic Party and the personal email account of John Podesta, Hillary Clinton's 2016 presidential campaign chairman.

Three congressional probes are looking into Wikileaks and its founder Julian Assange (L) for their activity during 2016 election

The CIA, the National Security Agency, and the Federal Bureau of Investigation said Russian intelligence did the hacking

WikiLeaks published emails hacked from the Democratic Party and the personal email account of John Podesta

In a report issued in January, the CIA, the National Security Agency, and the Federal Bureau of Investigation said Russian intelligence did the hacking, and the GRU, Russia's military intelligence agency, sent hacked data to WikiLeaks via intermediaries.

The Senate Intelligence Committee is investigating who gave WikiLeaks the hacked Democratic National Committee data that WikiLeaks published in July 2016, which included more than 44,000 emails and 17,000 attachments, the sources said. So far, its inquiries are still at an early stage, the sources said.

Senate Judiciary Committee leaders have asked Jared Kushner, Trump's son-in-law, for emails related to WikiLeaks.

The House Intelligence Committee has questioned Roger Stone, a longtime friend of President Donald Trump and a veteran political operative who promoted WikiLeaks' disclosures of the emails on Twitter.

The FSB security service , the successor to the KGB, building in central Moscow on December 30, 2016

The US intelligence community said Russian intelligence did the hacking, and the GRU (pictured), Russia's military intelligence agency, sent hacked data to WikiLeaks

After initially refusing to identify an intermediary he dealt with who was in contact with Assange, Stone later told the committee it was Randy Credico, a left-wing comedian.

The committee sent Credico a letter asking him to appear voluntarily. When he declined to do so, the panel sent him a subpoena requiring him to give a deposition.

Credico's lawyer, Martin Stoller, said on Wednesday that Credico was considering whether to invoke his First and Fifth Amendment rights under the U.S. Constitution to avoid answering questions.

The House Intelligence Committee has questioned Roger Stone (pictured), a longtime friend of President Donald Trump, about the hacking last month

It is unclear whether Credico could help investigators uncover where WikiLeaks got the hacked Democratic emails.

In emails to Reuters, Stone has dismissed the intelligence agencies' conclusion about Russian hacking.

It is not known whether Robert Mueller, the Justice Department special counsel investigating possible Russian interference in the 2016 presidential election, is investigating WikiLeaks.

A U.S. lawyer for Assange, Barry Pollack, said Mueller's team had not contacted him.

Meanwhile, federal prosecutors in Alexandria, Virginia, are conducting a criminal investigation into how WikiLeaks obtained thousands of classified U.S. government documents, including CIA materials and most recently ultra-secret technical materials describing American spy agency hacking tools.

Law enforcement sources and Pollack said the probe began several years ago.

Assange has lived in the Ecuadorean Embassy in London for several years after taking refuge there when Swedish authorities sought his extradition in a sexual molestation case.