Almost 60 people have died in the attack, and more than 480 people were injured.
"We did see that he was gambling, but we did not see another individual", Mr Lombardo said, without revealing how soon before the massacre his punting took place.
Paddock's girlfriend, Marilou Danley, 62, who was in the Philippines at the time of the Sunday night bloodbath, was met by Federal Bureau of Investigation agents at the Los Angeles airport late Tuesday, according to a law enforcement official who wasn't authorized to discuss the matter publicly and spoke to The Associated Press on condition of anonymity.
Danley is considered a "person of interest" in the case, officials said.
Las Vegas massacre prompts more security at Chicago Marathon
He turned the gun on himself before officers were able to break into his room, number 135, in the gold glass skyscraper. Paddock opened fire on a music festival in Vegas on Sunday night, killing almost 60 people and wounding hundreds more.
"In that sense, I thank him for sparing my sister's life", she said, adding her sister was "really in love with Steve". And, ensconced within a locked room in a jam-packed hotel, shooting down at a crowd from very high up, he was virtually unassailable - at least for a span of many, many lethal minutes. Police say the shooter killed himself.
Agents are also expected to ask Ms Danley about the large quantity of weapons - 33 the past year - Paddock purchased and explosives and thousands of rounds of ammunition found at their Nevada homes. "What Congress can do - what Congress must do - is pass laws that keep our citizens safe", Senator Chuck Schumer, Democrat of NY, said on the Senate floor on Monday, October 2.
As of yet, no motive has been worked out, with Clark County Sheriff Joseph Lombardo saying they don't know what his belief system was and family members ruling out religious or political motives.
The search for Danley initially spanned several countries, with conflicting reports that she could have been in Japan or the Philippines at the time of the shooting. Lombardo later said the 62-year-old woman was located and not believed to be involved in the shooting.
NBC News reported that Paddock wired $100,000 to the Philippines last week, but NPR has not independently verified that report. Ed Turner, a former police officer who owns a gun shop in Stockbridge, Georgia, said he's seeing a run on bump stocks since the shooting.