The preliminary report was submitted to the prosecutors on Monday. It emphasizes that it is too early to say exactly how high levels of cocaine are involved.
The final report is not expected until several weeks from now.
The autopsy has previously established that the cause of death was "external and internal bleeding", and that the head injuries were severe enough to have caused his death.
Liam Payne, 31, died after falling from the third floor of a hotel in Argentina's capital Buenos Aires on October 16. The police were alerted to the hotel after a call about "an aggressive man who may have been under the influence of drugs and alcohol".
When they arrived, Payne was found in the hotel's courtyard, where he is believed to have landed after falling from the third floor. He was pronounced dead at the scene.
The police are also looking for a man who is suspected of having supplied Liam Payne with drugs. The suspicions are directed against a hotel employee.
