An Australian former friend of Las Vegas mass shooter Stephen Paddock has spoken of his horror as he watched the chilling bodycam footage of police on the scene, for the first time.

Adam Le Fevre spoke to A Current Affair in a world exclusive interview, offering his insight and experience of Paddock, who he met several times in recent years.

Mr Le Fevre had previously had a relationship with the sister of Marilou Danley, Paddock's Filipino-Australian partner.

Mr Le Fevre said he had tried to avoid watching the coverage of the massacre, trying to "take stock" of what happened.

Adam Le Fevre and Stephen Paddock in a drone-captured photo.

Gunman Stephen Paddock.

Watching the police bodycam footage for the first time, he was unable to contain his horror.

"And these poor people that were involved here didn't know what's going on and we sit here, and I know the person that's pulling the trigger," he said.

"It's a horrible thought. It's a horrible thought."

Adam Le Fevre knew Stephen Paddock.

Paddock (far right) shares a meal with Marilou Danley's family in the Philippines.

He was firm in his belief that Ms Danley, who is being interviewed by the FBI, would not have known of Paddock's plans.

"I believe if she had the slightest inkling something was not right, she would have shared that with her family and would have potentially been able to make a change," he said.

He said he did not see the relationship between Ms Danley and Paddock as "loving".

There were 59 people killed in the shooting.

More than 500 people were injured.

"I saw him talk to her abruptly and Liza (Werner, Ms Danley's sister) and I away from them questioned whether everything was alright with them," he said.

"Marilou, a lovely woman, seemed very nervous and jittery around Steve.

"He would talk to her in a condescending way and while I was concerned I thought it was part of his nature."

Mr Le Fevre came to know Paddock after joining him on a trip to Las Vegas and travelling with him on two occasions to the Philippines in recent years.

As well as holidaying with Stephen Paddock and Marilou Danley in Las Vegas, Mr Le Fevre also visited their home in the nearby Nevada town of Mesquite.

He said Paddock had a “gun room” at the house and became defensive when Mr Le Fevre asked him casually about the US constitutional right to bear firearms.

Mourners hold a vigil at the site of the massacre.

“I raised that question with Steve and it’s something that he came back at me with an incredible degree of vigour,” Mr Le Fevre said.

“He was very strict and very firm on the fact that it’s a right. It’s the freedom of every American to participate, to own a gun and use it… when need be.

People flee during the attack.

“I was shocked. There was no compassion in regard to my question.”

In describing their trip to Las Vegas in 2015, Mr Le Fevre said he and his partner were accommodated in “out of this world, penthouse suites like you wouldn't believe” thanks to Paddock’s “high roller” status on the Vegas casino strip.

“He had no qualms in telling me of the millions that he'd used,” Mr Le Fevre said.

“He said as a professional gambler I operate with $1.5 million to $2 million a year and that can generate me anywhere between $200,000 to $300,000 a year.

“He was very intent with it - extremely intent.

“He was very much a calculated person. Everything he did seemed to be planned with precision.”

Ms Danley has claimed she knew nothing about any plans for a massacre.

She returned to the US this week to speak with the FBI about the shooting.

The former Gold Coast resident, 62, said in a statement that she loved Paddock and thought he was sending her away to the Philippines because he was breaking up with her.

She had been living with Paddock in Mesquite, Nevada, before the shootings.

Ms Danley also explained why Paddock had wired her $100,000 while she was in the Philippines.

“While there (Paddock) wired me money which he said was for me to buy a house for me and my family,” she said.

“I was grateful but honestly I was worried that first, the unexpected trip home and then the money was a way of breaking up with me, it never occurred to me in any way whatsoever that he was planning violence against anyone.”

Investigators at first denied claims from terrorist group ISIL that Paddock carried out the shooting at their behest, but later refused to rule out a terrorist connection.