The official investigation into the mass shooting that took place at the Route 91 Harvest Festival in Las Vegas in October of 2017 is closing, and investigators have been unable to determine a definitive motive for the crime.

Sixty-four-year-old Stephen Paddock killed 58 people and wounded more than 800 others when he opened fire into the crowd during Jason Aldean's headlining set on the closing night of the festival from his hotel room at the Mandalay Bay hotel contiguous to the concert site. Despite an in-depth 10-month investigation during which authorities meticulously reconstructed how Paddock planned and carried out the crime, as they close the investigation, the central question remains unanswered: What drove this "unremarkable man," in the words of Clark County Sheriff Joe Lombardo, to carry out the deadliest shooting rampage in modern U.S. history?

Investigators conducted hundreds of interviews and put in thousands of hours of investigative work, Time reports. Though they don't know Paddock's motive, they say he did have a "troubled mind" in the months leading up to the crime. They have found no evidence of a conspiracy or a second gunman, and no other people will be charged in connection with the crime. Paddock took his own life as authorities closed in on his hotel room after his shooting spree.

The Victims of the Las Vegas Shooting

Four-hundred-and-fifty of the Las Vegas victims banded together to file suits against both MGM Resorts and concert promoter Live Nation after the shootings, claiming negligence. In July of 2018, MGM Resorts International filed federal lawsuits against more than 1,000 victims. They are not seeking money from the victims, but they are seeking for all existing litigation to be dismissed.

Investigators concluded that Paddock's attack had no link to international terrorism, but MGM, which owns Mandalay Bay and the concert site, has invoked a provision of a federal law that was put into place after the Sept. 11 terrorist attacks, asking a federal court to qualify the Las Vegas mass shooting as an act of terrorism. That would allow them to declare that MGM Resorts bears no liability to either the survivors of the shooting or the victims' families.

Watch Lindsay Ell's Incredible One-Woman Performance for RISERS!

Photos From the Route 91 Shooting Show Kindness Amidst Chaos

More From KIKN-FM / Kickin' Country 99.1/100.5