Police say they do not expect to file charges against the girlfriend of a gunman who killed 58 people in Las Vegas in October.
Marilou Danley, girlfriend of gunman Stephen Paddock, had previously been named a person of interest in the case.
Sheriff Joe Lombardo told a news conference that police still did not know the motive for the mass shooting.
Paddock opened fire on hundreds of concertgoers from a 32nd floor window of the Mandalay Bay hotel.
It was the deadliest mass shooting in modern US history.
Sheriff Lombardo told reporters that investigators believed Paddock had acted alone but that the FBI was investigating "a person of interest" whom he could not identify.
He said 851 people attending the music concert on Las Vegas Strip were injured, including 422 who had wounds associated with gunfire.
In a public update to the investigation on Friday, he revealed that Paddock had searched for other potential targets and taken photographs of possible sites.
Sheriff Lombardo said Paddock had also searched online for tactics used by police and Swat teams.
During the investigation child pornography images had been found on Paddock's laptop computer, he added.
"This report is not going to answer every question or even answer the biggest question as to why he did what he did," the sheriff said.
After the shooting, officers stormed the hotel room and found Paddock dead from a self-inflicted gunshot wound. He had smuggled 24 weapons and thousands of rounds of ammunition into the hotel, concealed in 10 suitcases.
She said she had known him as a "kind, caring, quiet man".