United States President Donald Trump’s key ally Roger Stone was arrested in Florida on Friday and charged with lying to Congress and obstructing an investigation into alleged collusion between Russia and the Trump campaign, AP reported. He has been charged with seven counts, including for making false statements, and witness tampering.

Special Counsel Robert Mueller is investigating alleged Russian interference in the 2016 presidential election.

The charging documents in the case included details about how Trump’s campaign associates allegedly contacted Stone in 2016 to ask him for advice on when to disclose that former Democrat candidate Hillary Clinton’s emails were stolen, Reuters reported. The investigation has not linked Stone with conspiring with WikiLeaks, the anti-secrecy website that shared the emails, or with the Russian officers who allegedly hacked them.

Trump and Russian President Vladimir Putin have denied allegations of collusion. Trump has referred to the investigation, which has filed charges against more than two dozen Russians and several people connected to Trump, as “a witch-hunt”.