The third floor room at the Casa Sur hotel where Liam Payne was staying is now sealed off with police tape.

Hotel guests walk up and down the corridor but a police officer is on guard to ensure nobody interferes with what is still the scene of an active investigation.

How and why did the One Direction star plummet to his death from the balcony of this room and was there any third-party involvement?

A 911 emergency call has already been leaked in which a hotel worker expresses concern for a guest who he believes to be under the influence of drugs and alcohol.

It is part of a stark picture emerging of the 31-year-old's final hours.

| Fans of Payne mourn his death in Argentina. Pic: AP

Sky News has seen police images from inside the room which authorities say was completely trashed.

The pictures show a TV screen smashed, unknown white substances and aluminium foil strewn across surfaces.

Other guests at the hotel in the upmarket Palermo district of Buenos Aires include a party of at least 20 people from the United States, in town for a friend's wedding.

For Doug Jones, it is his first time out of the US and he did not know what to expect.

He's staying in the room opposite where Payne was. The day before the singer died, Doug says he saw hotel staff coming in and out of the room carrying furniture.

"I assumed they were doing renovations because they had tool kits and drills," he said.

On the day that Payne died, Doug said he heard lots of commotion coming from the room.

"A lot of crashing and banging and shouting," he said. It culminated around 5pm, Doug says, when he heard a "violent, manly scream".

| Forensics at the hotel. Pic: Reuters

He came outside and on to the tree-lined street outside, with its smart restaurants, bars and high-end shops.

It was suddenly filled with police cars. It was then he realised something tragic had unfolded.

"I'd heard of One Direction but I wouldn't recognise Liam Payne, but some of the women who are part of the wedding had seen him in the elevator," he said. "Now there's a police woman sitting outside my room watching his room. I'm not sure how long she'll be there."

Other guests say they had seen Payne engaged in a heated discussion with a woman in the hotel lobby just hours before he died.

| Pictures from Payne's hotel room in Buenos Aires. Pic: Buenos Aires Police

A 15-minute drive across town is the judicial morgue, where forensic experts assess that Payne had suffered 25 separate injuries in the fall, including massive internal and external bleeding. His injuries were incompatible with life, they said.

Baleria Linares, a 21-year-old college student who lives just a few streets from the Casa Sur hotel, has returned to join other fans who gathered to weep and sing One Direction songs. "We are together in our grief," she said.

"Liam means so much to me," she added between sobs, "he helped me through a hard time in my life. When I was happy I listened to them, when I was sad I listened to them. I love them with all my heart. But I know that he's resting now."

'They saved my life at some point'

Some fans clutch bouquets, others pin notes to a nearby tree which is decorated with images of Payne.

"You'll be always in our hearts," one reads.

Morena Farias Gomez is sobbing as her friend tries to comfort her. "It is devastating news," she said, "I've been a fan of One Direction for 10 years. I think they saved my life at some point, they were my teenage years, I grew up with them."

The grief is real, here, but even more acute thousands of miles away with Payne's family in the UK as they wait to bring his body home.