Liam Payne: Three charged in connection with singer's death
Payne, 31, a father-of-one, was one of the most recognisable names in pop after appearing on The X Factor and rising to fame with the boyband One Direction in the 2010s.
Argentinian authorities have been investigating Payne's final days at the CasaSur hotel.
After the singer's death, police found substances in his hotel room, and destroyed objects and furniture. Hotel staff had made two calls to emergency services saying they had a guest who had taken "too many drugs and alcohol", and was "trashing the entire room", it was previously reported.
On Thursday,the public prosecutor's office said toxicology tests revealed traces of alcohol, cocaine and a prescription antidepressant in his body.
A post-mortem examination determined his cause of death as "multiple trauma" and "internal and external haemorrhage" as a result of the fall from the hotel balcony.
According to the prosecutor's office, medical reports also suggested Payne may have fallen in a state of semi or total unconsciousness.
The prosecutor's office say this rules out the possibility of a conscious or voluntary act by Payne, and they conclude he did not know what he was doing nor did he understand it.
In addition, authorities have carried out nine raids at homes in Buenos Aires.
They are also continuing to investigate Payne's broken laptop and other devices seized.
The prosecutor's office added it has examined more than 800 hours of video footage from security cameras in the hotel and on public roads, and received dozens of testimonies from hotel staff, family members, friends and medical professionals.
The singer's body was released to his family on Wednesday to be flown back to the UK.