The man suspected of opening fire at concertgoers attending a country music festival in Las Vegas on Sunday night was a local resident with no prior criminal convictions in the state of Nevada.

Stephen Paddock, 64, lived just 90 minutes outside Las Vegas in the city of Mesquite, where he purchased a home in a retirement community for just over $369,000 in 2015 according to public records.

He lived there with his 62-year-old girlfriend Marilou Danley, the same woman police announced they were seeking to question on Sunday night as they began their investigation into the horrific terror attack.

Paddock had both hunting and fishing licenses according to public records, as well as his pilot's license, but no criminal record in the state of Nevada.

The retired accountant had worked as an internal auditor at Lockheed Martin for three years in the late 1980s, and previously managed apartment building complexes in Mesquite, Texas and California.

Paddock was also the son of Benjamin Hoskins Paddock, a serial bank robber who ended up on the FBI Most Wanted list back in 1969 when he escaped from federal prison in Texas while serving a 20 years sentence.

The FBI kept him on the list for the next eight years, and he was eventually found one year after he was removed from the list in 1978 while outside an Oregon Bingo hall.

The agency said that the fugitive had been 'diagnosed as psychopathic' and also had possible 'suicidal tendencies. Paddock had committed suicide by the time police breached the door to the room from which the gunman had opened fire at the Mandalay Bay Resort just after 10pm on Sunday night. 

It marked the end of what has now become the deadliest mass shooting in modern US history, which left at least 58 dead and 515 injured.

The attack played out as Jason Aldean performed on stage to close out the third and final day of the Route 91 Harvest Music Festival, which was taking place across the street from the resort.

Over 22,000 people were in attendance at the event, and described the attack as 'nonstop gunfire,' which only stopped when the gunman went to reload his weapon. 

It is not yet known what weapon or weapons the gunman used in the attack.

Police said in a press conference early Monday that that they discovered in 'excess of 10 rifles' in the room, and that Paddock's death was the result of a self-inflicted gunshot wound.