(CNN) We will likely never know why Stephen Paddock shot into a crowd of Las Vegas concertgoers, killing 58 people in the deadliest mass shooting in modern US history.

The FBI has concluded its investigation into the October 1, 2017, massacre without finding a clear motive for Paddock's actions.

But a list of key findings released Tuesday found Paddock was similar in many ways to other active shooters: He had no identifiable grievance and had a desire to die by suicide.

The Las Vegas Review Panel of the FBI's Behavioral Analysis Unit determined that Paddock acted alone, and that his attack "was neither directed, inspired, nor enabled by ideologically motivated persons or groups," the FBI said.

After almost 12 months of analyzing evidence and information, the panel concluded "there was no single or clear motivating factor" behind the attack, and that Paddock's actions were inspired by obtaining "a certain degree of infamy via a mass casualty attack," the FBI said.

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