A criminal complaint said Robertson posted threats on Facebook against Biden and a prosecutor pursuing criminal charges against former President Donald Trump.
Agents of the Federal Bureau of Investigation during a raid on Wednesday shot dead a man in Utah identified as Craig Robertson, who posted violent threats against the US President, Joe Biden and other officials online.
BBC reports that the FBI agents were attempting to serve an arrest warrant on Robertson at his home in Utah, just hours ahead of a planned visit to the state by President Biden.
The FBI however declined to give more details but the raid reportedly happened at about 06:15 local time in Provo, about 40 miles (65 km) South of Salt Lake City.
A criminal complaint said Robertson posted threats on Facebook against Biden and a prosecutor pursuing criminal charges against former President Donald Trump.
The criminal complaint outlined messages that Robertson made on Facebook including pictures of guns and threats to kill Mr Biden and Alvin Bragg, the Manhattan district attorney leading an investigation into a hush-money payment by Mr Trump to an adult film star.
The complaint noted that other messages targeted US Attorney General, Merrick Garland and New York Attorney General, Letitia James.
Robertson was said to have posted on Facebook saying, "I hear Biden is coming to Utah. Digging out my old ghillie suit and cleaning the dust off the M24 sniper rifle."
It was just one of dozens of violent messages and photos of weapons posted on two of Robertson's Facebook accounts, and the complaint said Robertson came to the attention of federal agents in March after he posted a threat against Mr Bragg on Truth Social, the social network owned by Trump, as the company alerted the FBI's National Threat Operations Center.
FBI agents then visited the suspect, who told them that the post was a "dream" and ended the conversation by saying, "We're done here! Don't return without a warrant!"
It was reported that later posts by Robertson referenced his encounter with the agents, showed him in camouflage used by snipers, and repeatedly threatened public officials, and as late as Tuesday, he posted, "Perhaps Utah will become famous this week as the place a sniper took out Biden the Marxist."
Biden is said to be making his first visit to Utah as president on Thursday, with a visit to a veterans' hospital and a fundraising event in Park City.