Forensic pathologist Dr Beng Beng Ong from the University of Queensland was the first witness for the defence in Jakarta’s most notorious murder case.
Australian resident Jessica Wongso, 27, is accused of murdering her friend Mirna Salihin in January by putting cyanide in her coffee.
But Dr Ong told the court that cyanide was not the cause of Ms Salihin’s death.
Prosecutors had tried but failed to stop Dr Ong from giving evidence and questioned his visa status
Hours after he gave evidence, Dr Ong attempted to leave the country but his passport was confiscated by immigration authorities.
Indonesian authorities said Dr Ong entered the country on a tourist visa instead of a working visa.
Wongso lived in Sydney for seven years before going to Jakarta on holidays where she met up with Ms Salihin.
The pair had become friends while studying at the Billy Blue Design College in Sydney.
Ms Saluhin died shortly after drinking a Vietnamese iced coffee ordered by Wongso in an upmarket Jakarta cafe.
Police say Wongso poured cyanide into the coffee.
The case against Wongso was almost dropped by Indonesian prosecutors because of a lack of evidence.
But Australia’s Justice Minister Michael Keenan approved the handing-over of an Australian Federal Police file that detailed Wongso’s erratic and worsening behaviour over the 12 months before the alleged murder.
The file contained confidential police intelligence reports that detail four suicide attempts that required hospitalisation, threatening behaviour towards colleagues, a major alcohol-fuelled road accident, and an Apprehended Violence Order taken out against her by her ex-boyfriend following the destruction of his car by a vandal.
Police in Jakarta used the file to justify their interest in Wongso, stating publicly that she had many interactions with police in Australia.