Donald Trump's longtime friend Roger Stone has pleaded not guilty to charges in the special counsel's Russia investigation. Stone appeared on Tuesday for his arraignment at the federal courthouse in Washington after spending the weekend blasting special counsel Robert Mueller's case against him as politically motivated.The self-proclaimed dirty trickster was arrested last week during a pre-dawn raid at his Florida home. He is charged in a seven-count indictment with obstruction, lying to Congress and witness tampering.Prosecutors say he lied about the contents of his discussions with the Trump campaign involving WikiLeaks and hacked material damaging to Hillary Clinton that the anti-secrecy group released during the 2016 campaign.Stone is also accused of corruptly influencing the testimony of another witness.Stone arrived in a black SUV wearing an all-blue suit and tie. He waved to a small crowd of supporters and protesters, including some yelling, "Lock him up".A longtime confidant of the president, Stone is the sixth Trump aide charged in Mueller's investigation. The indictment does not accuse Stone of coordinating with Russia or with WikiLeaks on the release of hacked Democratic emails. But it does allege that he misled lawmakers about his pursuit of those communications and interest in them. The anti-secrecy website published emails in the weeks before the 2016 presidential election that the US says were stolen from Democrats by Russian operatives.Stone, who has alleged without evidence that the FBI used "Gestapo tactics" in arresting him, said he did nothing more than exercise his First Amendment rights to drum up interest with voters about the WikiLeaks disclosures. He said he never discussed the issue with Trump."That's what I engaged in. It's called politics and they haven't criminalised it, at least not yet," Stone said on Sunday on ABC's "This Week"."All I did was take publicly available information and try to hype it to get it as much attention as possible, because I had a tip, the information was politically significant and that it would come in October," he added.Tuesday's arraignment could inspire the same circus-like atmosphere that surrounded his Friday court appearance in Florida, where Stone emerged from the building in a blue polo shirt, flashed a Richard Nixon victory sign, predicted his vindication and vowed that he would not "bear false witness against the president, nor will I make up lies to ease the pressure on myself".All the while, jeering spectators shouted "Lock Him Up!" while others in the crowd cheered him on.It's unclear whether Mueller's prosecutors will look to have Stone locked up pending trial or whether they will simply recommend conditions that would allow him to remain free on bond. It's also possible that US Magistrate Deborah Robinson might impose a gag order to prevent Stone from discussing the case.