Liam Payne could have been in a "state of semi or unconsciousness" when he fell to his death.
The 31-year-old singer fell from the third-floor balcony of a hotel in Buenos Aires, Argentina, on Wednesday 16 October.
On Thursday, the National Criminal and Correctional Prosecutor's Office in Argentina made a statement about the accident.
"The prosecutor's office indicated that, due to the position in which the body was left and the injuries from the fall, it is presumed that Payne did not adopt a reflex posture to protect himself and that he could have fallen while in a state of semi or total unconsciousness," the office said in a statement.
The incident took place at the CasaSur Palermo Hotel where the One Direction star was staying as a guest.
The National Criminal and Correctional Prosecutor's Office confirmed it would be investigating the event as an "inconclusive death".
It has been indicated the musician was alone when the fall took place and he appeared to be "going through some kind of outbreak due to substance abuse".
Payne died of multiple traumas and "internal and external haemorrhage" as a result of the fall, a post-mortem examination report has revealed.
The prosecutor's office also confirmed five witnesses have been questioned to help reconstruct what happened in the time leading up to his death.
According to eyewitnesses, Payne had been acting erratically and had smashed his laptop in the hotel lobby, forcing hotel staff to guide him up to his room.
In a 911 call released on Thursday, a hotel worker was heard telling the emergency services the star needed help.
"We have a guest," the man, only known as Estaban was heard saying. "When he is conscious, he is destroying his room and we need you to send someone, please.
"We need you to send someone urgently because I don't know if his life is in danger."
Payne had fallen from the balcony by the time emergency services had arrived.
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