A source close to Liam Payne has said that he did not commit suicide and could have been saved.

In the most comprehensive account of the One Direction star's final hours, The Mail on Sunday has been told those closest to Liam believe if an ambulance had been called immediately when he collapsed in a Buenos Aires hotel lobby on Wednesday – rather than some time later when he was back alone in his third-floor room – he 'would have lived.'

The source said: 'Liam didn't have to die. Liam didn't want to die. He had promised us all he would never commit suicide. He was looking forward to the future.

'If someone had called an ambulance when he collapsed in the hotel lobby instead of taking him back to his room and leaving him in there alone, in a psychotic state, he would still be with us.'

The source also revealed:

• Liam had been 're-working' his favorite One Direction track 'Fireproof' on his computer just hours before his death. 
• He was in Argentina to renew his US visa and had passed medical and psychological tests days before which proved he was 'totally clean.' 
• He was in 'good spirits' and had been planning to fly back home to girlfriend Kate Cassidy in Miami on Friday. 
• His final meal was his favourite, chocolate-chip cookies.

The 31-year-old singer died instantly after plunging 45ft from his third-floor hotel room balcony onto the patio below at 5.04pm on Wednesday.

Police found drugs in his room including 'cristal', a potent hallucinogenic that causes blackouts and psychotic episodes.

The source said: 'Where did Liam get the drugs when he had no money?'

Multiple police sources have said investigators believe someone in the hotel supplied him with drugs. There have been unconfirmed reports that the hotel conducted an internal probe and fired at least one employee.

Last night investigators told the MoS the probe into the star's death 'is ongoing' but said charges against those who supplied the drugs 'were imminent.'

Liam arrived in Argentina on September 30 with his girlfriend Kate and close friend Roger Nores. The source said: 'Liam's US visa was expiring and he had to leave America to renew it so he decided to go to Buenos Aires to see Niall Horan perform and get his new visa.'

But when Liam went to the US embassy in Buenos Aires the week before last he found officials had Googled him and discovered he had spent multiple stints in rehab for drugs and alcohol.

'They ordered him to do medical tests, see a doctor, do bloodwork and x-rays and see a psychiatrist and that was all done the first week. Liam thought the trip would only last a few days but because of all the tests he ended up getting stuck there.'

After spending last weekend at a polo farm outside Buenos Aires, girlfriend Kate flew back to Miami on Monday to care for the couple's dog while Liam checked into the CasaSur hotel.

'He had no money and his credit cards weren't working, so he was spending all his time in the room.

'On Tuesday he asked for a McDonald's. He was happy and in good spirits.

'The test results all came back totally clean on Tuesday and he had an appointment at the embassy to get his passport stamped with the visa on Thursday and then he was going to leave Argentina immediately.'

The source said a family friend visited him around 10am that morning to deliver his favourite 'American style' chocolate-chip cookies from a bakery three blocks from the hotel.

'He seemed a bit tipsy, like he had been drinking, but wasn't in a bad state. He was happy.

'He was replicating Fireproof on his computer. He loved recreating instrumentals and that was his favourite One Direction song. He was redoing the beat. He was in a good place, planning for the future, looking forward to going home to Miami to his girlfriend and his dog.'

Liam and his friend had coffee before the friend left.

The singer ordered whisky and champagne from the hotel bar before returning to his room.

Around 11am police say two prostitutes visited his room but left at 3pm after a row because he could not pay them cash.

Witnesses saw Liam arguing in the lobby with the women.

Around 3pm the hotel called Roger Nores, a friend of Liam's, to report the singer was causing a disturbance in the lobby.

Mr Nores came and apologised to onlookers, telling them 'he's a really nice guy' and took him to his room before leaving to run errands.

Hotel guest Brett Watson from Chicago told ITV that Liam came back down to the lobby several times. At one point he lay on a sofa in the lobby playing on his computer. Mr Watson said: 'There was an incident where he was very frustrated and was smashing his laptop in the lobby.'

There have been reports that was in reaction to receiving a mystery email, but sources say they have 'no idea' what message may have caused Liam to explode. Mr Watson said: 'The final time he came back down he actually passed out in the lobby of the hotel, looked like he was convulsing a little bit and had to be physically taken back to his room.'

The source said: 'If Liam was convulsing. why didn't the hotel call an ambulance immediately?

'That is what no one can understand. He never convulsed before.

'If he was that sick why did someone take him back to his room and leave him there alone, with an open door to the balcony?'

A hotel employee later called 911 to report Liam was smashing up his hotel room and to say they were worried he might jump.

The source said: 'If they were worried he might jump, why didn't someone go and sit with him? Why was he left alone?

'Did they treat him differently because he was a celebrity? If he had been a regular person would they have called an ambulance? Maybe they were worried about a scandal.

'If Liam was in a psychotic state he didn't know what he was a doing. He could have been trying to leave his room and he went to the balcony thinking it was the room exit and accidentally fell.

'We are tormented by the fact he was left alone in his room after he had convulsions and was clearly in a psychotic state.

'There are so many questions. Who supplied the drugs to him? Why did they take him back and leave him alone in his room? That was stupid and reckless. Leaving a person having a psychotic breakdown alone in a room with an open balcony is like giving someone a loaded gun. He didn't know what he was doing. He was out of it.

'He may have been trying to leave the room.'

Liam's father Geoff arrived in Buenos Aires on Friday to identify his son's body. He was accompanied by long-time One Direction bodyguard Paul Higgins.

Funeral arrangements will be made once Liam's body has been repatriated to the UK, which may take days.

The source added: 'The narrative so far has been wrong. People have been saying Liam relapsed on drugs and wanted to kill himself because his life was so bad.

'That wasn't the case. He was in a good place. He was happy and making plans for the future with Kate who he loved. Someone gave him drugs and those drugs caused a psychotic event.

'The tragedy is if someone had called an ambulance when he collapsed in the lobby and was convulsing, he would still be alive.'

Additional reporting: Heather Briley, Federico Fahsbender and Daniel Bates