The FBI is investigating a new "person of interest" in connection with the Las Vegas shooting, the county sheriff has said.

Fifty-eight people died in the massacre by gunman Stephen Paddock, who opened fire on concert-goers from a 32nd-floor suite at the Mandalay Bay hotel on the Las Vegas strip in October.

Announcing the release of a preliminary investigative report into the shooting, the sheriff of the Las Vegas Metropolitan Police Department said he did not believe charges would be filed against Paddock’s girlfriend, who was initially a focus of the investigation.

However, he said the FBI was investigating another person of interest, but would not identify them.

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We do not anticipate charges being brought forward against Marilou Danley, Clark County Sheriff Joseph Lombardo said.

Paddock is still believed to be the only suspect involved in the shooting, he said, adding: There was only one person responsible and that was Stephen Paddock.

Ms Danley shared Paddock’s retirement community residence in Mesquite, Nevada, northeast of Las Vegas, before leaving for the Philippines in mid-September.

She said through her attorney a few days after the shooting that she told the FBI she had no idea Paddock was planning violence against anyone.

Some 422 people were injured by gunshots and the total number of injuries associated with the incident was 851, Mr Lombardo said.

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According to the police report, Ms Danley recalled Paddock behaving strangely during an earlier stay at the Mandalay Bay in early September 2017.

She observed Paddock constantly looking out of the windows of the room, which overlooked the Las Vegas Village venue, the report said.

Ms Danley also described how Paddock’s demeanour changed over the course of the year leading up to the shooting, saying he became distant and germaphobic.

He also began to buy firearms, which Ms Danley believed was a hobby, according to the report.

It also said Paddock’s primary care doctor described him as odd with little emotion, and said he may have been bipolar, but Paddock would not discuss it and refused antidepressants.

Mr Lombardo said police still do not know why Paddock carried out the killings.

This report is not going to answer every question or even answer the biggest question as to why he did what he did, he said.

He added that the 81-page report into the shooting also includes details of Paddock’s disturbing search history on his computers, including his study of ballistics and SWAT tactics.

Police also recovered several hundred indecent images of children on Paddock’s laptop, the report said.

(c) Sky News 2018: FBI investigates new ‘person of interest’ over Las Vegas massacre