He also said 19-year-old Heather Mack, who is pregnant, and her boyfriend Tommy Schaefer were being transferred from police cells to the resort island's notorious Kerobokan jail, where prisoners live in cramped, filthy conditions and drug abuse is widespread.
The battered body of Sheila von Wiese Mack, 62, was found in a suitcase in the boot of a taxi in front of an exclusive hotel in the upscale Nusa Dua resort area in August.
Prosecutor Eddy Artha Wijaya told reporters in the Balinese capital Denpasar that police had finished their investigation and handed responsibility to the prosecution service.
"We have received the case file from the police," he said. Prosecutors have an initial 20 days to draw up charges and Wijaya said he hoped the pair would face trial in January.
Also Read
If the case does proceed to court, Mack and Schaefer will be formally charged at their first appearance, which is the usual procedure in the Indonesian legal system.
Mack's lawyer, Raja Nasution, insisted that "she will be more comfortable there as it's bigger". He added that she would go to hospital every month to check on the progress of her pregnancy.