Shooter Stephen Paddock went to great lengths to plan and cover up his attack at Las Vegas country music festival Route 91 Harvest Festival last October. According to new documents, his intent was to thwart the later investigation.

Federal court documents unsealed last week did not reveal a motive or co-conspirators, though the New York Times reports that Paddock attempted to hide or destroy digital media, used at least three cell phones, including one prepaid phone, and relied on anonymous communication devices to keep his plan a secret. The F.B.I. was not able to unlock one of his three phones, but they believe that if it exists, information relating to a conspiracy would be found within.

Prior to the attack Paddock spent roughly 12 months purchasing weapons, ammunition and accessories online to use in the massacre. Glass cutters, suitcases, a gas mask and body armor were among the other items authorities found in Paddock's Mandalay Bay hotel room, where he shot himself after firing on thousands of country music fans, killing 58.

The gunman's girlfriend, Marilou Danley, remains an important person in the ongoing investigation, if only to provide more detail about Paddock's actions and mental state leading up to the Route 91 Harvest Festival shooting. Danley has not been charged with anything, but did tell law enforcement they'd find her fingerprints on the ammunition he used, as she would occasionally help him load magazines. According to the Times, "the F.B.I. said there was no evidence that she knew of his plans or had been deceptive, but it cautioned soon after the shootings that she was still the 'subject of intensive review.'" Danley was out of the country at the time of the shooting. She later acknowledged to investigators that Paddock's physical and mental health had been deteriorating.

Authorities have focused on her social media accounts, and the new documents indicate that she made her Facebook page private just two-and-a-half hours after the shooting, then deleted it two hours after that. When authorities searched Paddock's email accounts, they found two addresses exchanging messages about bump stocks — a device used in the shooting to make his fire more rapid. However, they believe both email accounts were Paddock's.

"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 email accounts," documents read.

In addition to the dead, more than 500 patrons were injured when Paddock opened fire as Jason Aldean was performing his closing set at Route 91 Harvest Festival.

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