Liam Payne died of multiple traumas and internal and external bleeding caused by a fall from a third-floor hotel balcony in Buenos Aires, the Argentinian prosecutor’s office has said. An autopsy showed that the pop star’s head injuries were sufficient to cause death.

An investigation – including the interview of five witnesses in an attempt to reconstruct the 31-year-old musician’s final hours – indicated he was alone at the time of the fall. Substances were seized from Payne’s hotel room indicating alcohol and drug consumption.

The former member of One Direction died on Wednesday at 5pm local time. Guests at the Casa Sur hotel told the Guardian they heard banging and shouting for hours before Payne fell.

“I thought they were doing construction, there was so much banging, doors slamming, most of the day. It was loud, bizarre,” said Doug Jones. “Later I heard the sirens, thinking perhaps there was a fire somewhere. And then I heard a very loud scream.”

A hotel receptionist called emergency services to notify police of an “aggressive man who could be under the effects of drugs and alcohol”, according to Reuters. The hotel manager said he heard a loud noise at the back of the hotel, and when police arrived they found that a man had fallen over the balcony in his room.

Photos purporting to show Payne’s room in disarray, published in local news and online, were believed to have been taken by hotel employees, sparking a backlash about journalistic ethics.

Payne’s family said in a statement that they were “heartbroken” by his death. “Liam will forever live in our hearts and we’ll remember him for his kind, funny and brave soul. We are supporting each other the best we can as a family and ask for privacy and space at this awful time.”

One Direction were formed on The X Factor in 2010. Host Dermot O’Leary paid tribute to Payne, describing him as “a joy” who “had time for everyone, [was] polite, grateful, and was always humble”.

Ronnie Wood – who performed with the band when they returned to guest on the show in 2014 – said it had been “a pleasure to work with him”, while pop star Charlie Puth, who co-wrote Payne’s 2017 solo song Bedroom Floor, called him a “major artist”.

Payne’s former One Direction bandmates, Harry Styles, Louis Tomlinson, Zayn Malik and Niall Horan, said on Thursday evening they were “completely devastated” and will miss the singer “terribly”.

The four said in a signed statement: “In time, and when everyone is able to, there will be more to say. But for now, we will take some time to grieve and process the loss of our brother, who we loved dearly.

“The memories we shared with him will be treasured for ever. For now, our thoughts are with his family, his friends, and the fans who loved him alongside us. We will miss him terribly. We love you Liam.”

Cheryl Tweedy, with whom Payne had a son, Bear, in 2017, has yet to comment.

Rebecca Ferguson, who was the runner-up in the seventh series of The X Factor, in which One Direction placed third, and has been outspoken about abuse within the music industry, recalled meeting Payne in a taxi from Euston station to the show.

“I can’t help but think of that boy who was hopeful and looking forward to his bright future ahead,” she tweeted.

“I’ve spoken for years about the exploitation and profiteering of young stars and the effects – many of us are still living with the aftermath and the PTSD. Many of us are devastated and reflective today as it has finally taken its first victim.”