NEW YORK (NYTIMES) - As he meticulously planned the Las Vegas attack, the man responsible for the worst mass shooting in modern US history took elaborate steps to stymie the inevitable law enforcement investigation, according to federal court documents unsealed on Friday (Jan 12).
The FBI search warrants shed new light on the degree to which the gunman, Stephen Paddock, who killed 58 people and wounded more than 500 others after opening fire from a hotel room in October, planned the attack and prepared for the aftermath.
One of the warrants described how Paddock "destroyed or tried to hide digital media devices."
Investigators said he used anonymous communications devices, including a prepaid cellphone, to cover his tracks, and employed a "level of sophistication which is commonly found in mass casualty events."
"Paddock planned the attack meticulously and took many methodical steps to avoid detection of his plot and to thwart the eventual law enforcement investigation that would follow," the FBI said.
Paddock's motive for the attack remains unknown.
The search warrants, which were approved by judges shortly after the shooting, said three cellphones belonging to Paddock were found in his Mandalay Bay hotel room, including two that investigators searched and one that they could not unlock without assistance.
An FBI agent wrote that he believed "if there were any information related to a potential conspiracy it would be found within" the locked phone, which used a Google operating system.
The warrants detail how law enforcement focused on Marilou Danley, the girlfriend of Paddock. She has not been charged and has spoken to investigators several times. Her lawyer has said she was not aware of Paddock's deadly plans.
The investigation is continuing, and the warrants show only the early stages of the investigation.
"She has been identified thus far as the most likely person who aided or abetted Stephen Paddock based on her informing law enforcement that her fingerprints would likely be found on the ammunition used during the attack," according to court documents.
She told investigators she occasionally helped him load magazines. The FBI said there was no evidence that she knew of his plans or had been deceptive.
But the FBI cautioned at the time that she was still the "subject of intensive review." Danley corroborated much of what had been previously pieced together by investigators but she has been adamant that she had no prior knowledge of Paddock's intentions to conduct the attack.
According to the documents, it appears that Paddock relied on the Internet to buy many of the items used in the attack, including guns and ammunition, during the 12 months beforehand.
He spent "significant time and expense prior to the attack purchasing and caching weapons" and other items such as glass cutters and suitcases. Authorities have said he used the glass cutters so he could fire out of his hotel window into the crowd below attending a music concert.
Much of what investigators found in the hotel room is known but the warrants added details.
The FBI said there were hundreds of rounds of spent ammunition as well "preloaded high-capacity magazines" found in suitcases that Paddock had brought to room. There were also range finders, body armour and a homemade gas mask.
Investigators also revealed that Paddock may have been treated for "unidentified medical conditions." In October, Danley told investigators that Paddock's physical and mental health had seemingly deteriorated in recent months.
In an affidavit submitted as part of a search warrant application, an investigator said that access to Danley's e-mail account could "lead investigators to determine the full scope of Stephen Paddock's plan and Marilou Danley's possible involvement."
The authorities also requested information about several Instagram accounts they believed were connected to Danley.
In their requests for data from Instagram, investigators said they were seeking "evidence showing the possession, use, purchase or sale of firearms, firearms accessories, ammunition or explosives by Paddock."
They also sought information about Danley's "state of mind as it relates to the crime under investigation" and the identities of anyone who communicated with her about what would amount to violations of federal weapons laws.
At 12.30am, about 2 1/2 hours after the shooting began, Danley changed her Facebook account to private, investigators wrote in their affidavit. By 2.46am, she had deleted the account entirely.
In September, the court records suggested, Paddock ordered from Amazon a holographic weapon sight that investigators believe he used during the assault in Las Vegas.
On Friday night, Amazon listed the same model, which it described as "designed for close-in combat speed and versatility."
The price tag is US$429, Amazon said, adding that it "improves target acquisition, boosts accuracy and increases control."
The FBI also discovered e-mails between two accounts connected to Paddock. One from early July that indicated Paddock had begun taking steps to carry out the attack, referring to a "bump stock," an attachment that enables a semi-automatic rifle to fire faster.
In an e-mail Paddock sent on July 6 to an account that also possibly belonged to him, he wrote: "try an ar before u buy. we have huge selection. located in the las vegas area."
Another e-mail exchanged between the accounts said "for a thrill try out bumpfire ar's with a 100 round magazine." By "ar," Paddock was referring to rifles.
The affidavit later adds that "investigators have been unable to figure out why Stephen Paddock would be exchanging messages related to weapons that were used in the attack between two of his e-mail accounts" and that it was possible someone else was controlling one of the accounts.
If that was the case, the investigator said, the FBI needed to identify that person. Receiving a search warrant for that account "will lead investigators to determine the full scope of Stephen Paddock's plan," an FBI agent wrote to the judge.