Las Vegas shooter Stephen Paddock had visited the Middle East during a series of cruises, police have revealed.

Investigators remain stumped as to Paddock’s motives but said he visited the contentious region on a cruise.

He also took at least 11 other cruises to other destinations over the last several years, the AP reported.

The region, where Isis and other jihadi groups have a presence in some areas, may be of interest to security services because of speculation Paddock became radicalised.

Body cam footage shows officers during Las Vegas mass shooting

Extremist group Isis have repeatedly claimed responsibility for the shooting, which killed 58 people and wounded hundreds more.

The group claims he converted to Islam six months ago but no link has been proven to the organisation.

Clark County Undersheriff Kevin McMahill said investigators had "looked at literally everything" and still could not establish a clear motive.

They have been closely scrutinising his trips and other activities in a bid to understand why he decided to fire on a crowd of country music fans from the Mandalay Bay Hotel.

Investigators have chased 1,000 leads and examined Paddock's politics, finances, any possible radicalisation and his social behaviour — typical investigative avenues that have helped uncover the motive in past shootings.

In previous massacres, killers have left notes, social media postings or information on a computer, or even phoned police.

But information surrounding Paddock is scant. A cryptic notebook filled with numbers was found in the hotel room he used to shoot at the crowd.

The focus of the investigation has now turned to Paddock’s girlfriend, Marilou Danley, who was in her native Philippines at the time of the shooting.

She has been labelled a "person of interest," but is not in custody and is cooperating with authorities.

Ms Danley has told investigators she had not seen indications Paddock could become violent.

Las Vegas shooting – in pictures Show all 15 1 /15 Las Vegas shooting – in pictures Las Vegas shooting – in pictures People scramble for shelter at the Route 91 Harvest country music festival after gun fire was heard Getty Las Vegas shooting – in pictures People carry a person at the Route 91 Harvest country music festival after shots were fired David Becker/Getty Las Vegas shooting – in pictures People run from the Route 91 Harvest country music festival after gun fire was heard David Becker/Getty Las Vegas shooting – in pictures A handout photo released via Twitter by Eiki Hrafnsson (@EirikurH) showing concertgoers running away from the scene (C) after shots range out at the Route 91 Harvest festival on Las Vegas Boulevard EPA/Eiki Hrafnsson Las Vegas shooting – in pictures People lie on the ground at the Route 91 Harvest country music festival after hearing gun fire Getty Las Vegas shooting – in pictures A man in a wheelchair is taken away from the Route 91 Harvest country music festival after hearing gun fire David Becker/Getty Las Vegas shooting – in pictures People stand on the street outside the Mandalay Bay hotel near the scene of the Route 91 Harvest festival on Las Vegas Boulevard EPA/Paul Buck Las Vegas shooting – in pictures FBI agents confer in front of the Tropicana hotel-casino after a mass shooting during a music festival on the Las Vegas Strip Reuters/Las Vegas Sun/Steve Marcus Las Vegas shooting – in pictures Las Vegas police run by a banner on the fence at the Route 91 Harvest country music festival grounds after shots were fired David Becker/Getty Las Vegas shooting – in pictures An injured person is tended to in the intersection of Tropicana Ave. and Las Vegas Boulevard after a mass shooting at a country music festival Ethan Miller/Getty Las Vegas shooting – in pictures Metro Police officers pass by the front of the Tropicana hotel-casino after a mass shooting at a music festival on the Las Vegas Strip Reuters/Las Vegas Sun/Steve Marcus Las Vegas shooting – in pictures A woman sits on a curb at the scene of a shooting outside of a music festival along the Las Vegas Strip AP/John Locher Las Vegas shooting – in pictures A cowboy hat lays in the street after shots were fired near a country music festival in Las Vegas Getty Las Vegas shooting – in pictures Las Vegas Metro Police and medical workers stage in the intersection of Tropicana Avenue and Las Vegas Boulevard South after a mass shooting at a music festival on the Las Vegas Strip Reuters/Las Vegas Sun/Steve Marcus Las Vegas shooting – in pictures Sheriff Joe Lombardo (2-R) speaking during a press briefing in the aftermath of the active shooter incident on Las Vegas Boulevard EPA

Detectives believe Paddock may have been with a prostitute in the days before the massacre and have been questioning local sex workers.

In a possible sign he was contemplating massacres at other sites, he also booked rooms overlooking the Lollapalooza festival in Chicago in August and the Life Is Beautiful show near the Las Vegas Strip in late September, according to authorities.

Paddock also bought 1,000 rounds of.308-calibre and .223-caliber tracer ammunition from a private buyer he met at a Phoenix gun show, a law enforcement official said.