Robert Mueller, the former special counsel whose investigation into alleged Russian interference in the 2016 US election defined much of Donald Trump's first term in office, has died aged 81.
The cause of his death was not immediately clear. CBS News, the BBC US partner, confirmed his death.
With deep sadness, we are sharing the news that Bob passed away on Friday night, his family told the AP in a statement. His family asks that their privacy be respected.
Mueller previously led the Federal Bureau of Investigation (FBI) from 2001 to 2013, taking the office just days before the 11 September 2001 terror attacks. He is credited with reshaping it into a modern counterterrorism agency.
Mueller is survived by his wife of nearly 60 years, Ann Cabell Standish, their two daughters, and three grandchildren.
Mueller's special counsel inquiry put Donald Trump's 2016 campaign under a microscope, drawing harsh criticism from the US president. The president wrote on Truth Social on Saturday: I'm glad he's dead. He can no longer hurt innocent people!
Mueller's former employers and colleagues praised him as a longtime public servant. Both of the presidents he served under as FBI director - George W Bush and Barack Obama - paid tribute.
Bush, who appointed Mueller to lead the FBI, said he was deeply saddened by his death.
Obama called him one of the finest directors in the history of the FBI and commended his relentless commitment to the rule of law and his unwavering belief in our bedrock values.
The investigation resulted in multiple indictments and plea deals with former Trump campaign manager Paul Manafort, as well as national security adviser Michael Flynn. The 448-page Mueller report ultimately found that Russia interfered in the 2016 election, but did not establish that members of the Trump campaign coordinated in these activities.
During his investigations, Mueller's team was under scrutiny as they evaluated Russia's actions alongside Trump's campaign staff. Despite this, Mueller remained mostly silent, focusing instead on the substantial outcomes of his investigations and leaving the drama and discourse to unfold among political commentators.
Mueller was born in 1944, enlisted in the Marines during the Vietnam War, and graduated from the University of Virginia School of Law. He was unanimously confirmed as FBI director in 2001, serving for over a decade before retiring in 2013.
