Las Vegas Sheriff Joseph Lombardo shut down questions from a far-right conspiracy theorist during a press conference on last week's massacre.

Laura Loomer had asked about changes to the police timeline of Stephen Paddock's movements in the days and hours before he shot dead 58 people from his room at the Mandalay Bay Hotel.

Authorities initially said the 64-year-old checked in to the resort on September 28, three days before the massacre, but now believe he arrived on September 25.

Far-right trolls have seized upon the revision as evidence in support of various conspiracy theories, including claims of a false flag attack or cover-up of links to Isis terrorism.

"All of the evidence that is being leaked is further showing how the Deep State is covering it up," Ms Loomer has previously written on Twitter, describing the FBI as "the Federal Bureau of Islam".

But she was swiftly silenced by Sheriff Lombardo after asking a leading question about "timeline changes" at Monday's press conference.

“That’s not how I conduct press conferences” he told her.

“Please stop asking your question. There’s a decorum that we have here.”

He later confirmed authorities now believed Paddock had checked in to the hotel on September 25 and not September 28, although he added: "I'm under the belief he was not occupying the room between those dates."

Investigators remain mystified about Paddock's motive, and conspiracy theorists have taken advantage of the absence of information to promote groundless claims about the shooting.

InfoWars' Alex Jones, who has previously pushed falsehoods about the 9/11 terror attacks and Sandy Hook massacre, has depicted Paddock variably and without evidence as an Islamist terrorist, anti-fascist activist, and Democrat stooge.