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 finals days at the CasaSur hotel.
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 home in the Buenos Aires.
They are 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 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.