Washington (AFP) - Las Vegas concert shooter Stephen Paddock may have been seeking a "certain degree of infamy" when he carried out the worst mass shooting in recent US history, but no single or clear motive has been found for the 2017 attack, the FBI said Tuesday.
The conclusion was reached in a report released by the FBI Behavioral Analysis Unit, which looked into the October 1, 2017 massacre.
Paddock, a 64-year-old Nevada resident, fired more than 1,000 rounds down on the crowd at an open-air country music concert while perched in a 32nd floor room of the Mandalay Bay Resort and Casino.
Fifty-eight people were killed and another 869 injured, including 413 who suffered gunshot or shrapnel wounds.
Paddock, a wealthy retired accountant, then shot himself in the head as police moved in.
The Federal Bureau of Investigation said a panel of experts had conducted an analysis of Paddock's life and behavior leading up to the attack.
Paddock acted alone and was not motivated by any ideological or political beliefs, the FBI said.
"There was no single or clear motivating factor behind Paddock's attack," the report said.
"Throughout his life, Paddock went to great lengths to keep his thoughts private, and that extended to his final thinking about this mass murder," the FBI said.
- 'Desire to die by suicide' -
It said no suicide note or any other communications related to the planning of the attack were found.
"However, an important aspect of the attack was Paddock's desire to die by suicide," the FBI said.
"Paddock experienced an objective (and subjective) decline in physical and mental health, level of functioning, and financial status over the last several years of his life," it said.
"In reaction to this decline, Paddock concluded that he would seek to control the ending of his life via a suicidal act.
"Paddock's intention to die by suicide was compounded by his desire to attain a certain degree of infamy via a mass casualty attack," the FBI said.
Paddock may have been influenced in this regard by his memories of his father, the FBI said.
Paddock was one of four brothers who were raised by their mother after their father went to prison for bank robbery.
Benjamin Paddock, Paddock's father, was featured on the FBI's list of Top Ten Most Wanted Fugitives in 1968.
The FBI said that Paddock devoted detailed planning to the attack, using the internet to pinpoint a target site and spending a year buying weapons and ammunition.
"Despite Paddock’s research, planning, and preparation, the (FBI panel) found no evidence that he communicated his intent to commit an attack to others or that anyone was aware of his objective," the FBI said.
A separate investigation by the Las Vegas police were also unable to find a single motive for the attack. Their findings were released last year.
Paddock worked for the Internal Revenue Service after college and as an accountant for several major corporations.
A heavy gambler, Paddock was known to wager tens of thousands of dollars at a time and had lost a great deal of money in the years leading up to the attack, according to the Las Vegas police report.
Twenty-four guns were found in Paddock's hotel room including 10 AR-15 semi-automatic rifles, most of which were equipped with 100-round magazines.
Eighteen more guns were recovered from Paddock's residence in Mesquite, Nevada, and another seven from his home in Reno.