Authorities in Australia have detained a Malaysian police officer sentenced to death for the murder of 28-year-old Mongolian woman Altantuya Shaariibuu.
Ms Shaariibuu was shot in the head and her body blown up with explosives in a jungle near Kuala Lumpur in 2006.
Sirul Azhar Umar, a former body guard to the political elite, had his conviction reinstated last week in a Malaysian court but was on the run.
The case rocked the country when it first came to light.
It has for years been the subject of speculation about political conspiracies and has dogged Prime Minister Najib Razak - deputy prime minister at the time of the murder - who has been accused of interfering with the investigation.
The opposition has sought to link him to the case, but Mr Najib has repeatedly said that he had nothing to do with it and never met Ms Shaariibuu.
The Australian Broadcasting Corporation said Sirul - who was already thought to be in Australia - had been taken into custody by immigration officials in Brisbane on Tuesday.
The Australian Department of Immigration and Border Protection said only that it had "detained an unlawful non-citizen" and was "aware of the Malaysian authorities' interest in this individual".
But his detention was later confirmed by Malaysian police Inspector-General Tan Sri Khalid Abu Bakar.
He told the Bernama state news agency that police would begin discussions on extraditing Sirul to serve his sentence.
However, Australia has a policy of not extraditing people to countries where they face execution.
The remains of Ms Shaariibuu, a Mongolian model and interpreter, were found in a jungle in 2006.
Sirul and another policeman, Azilah Hadri, were found guilty and sentenced to death in 2009.
The police officers were acquitted in 2013 when a lower court ruled there had been gaps in the evidence against them. But on 13 January this year Malaysia's highest court overturned the acquittal and reinstated the death sentences. Sirul was not in court for the decision.
The two policemen, who belonged to the elite Special Action Unit protecting top lawmakers including Mr Najib, have always denied the charges against them.
Abdul Razak Baginda, a former associate of Mr Najib, was also arrested for abetting the murder but charges against him were eventually dropped. He later admitted that he had an affair with Ms Shaariibuu.
No motive was ever established for the murder and the case has long been a source of speculation about political conspiracies
Mr Umar has previously said he was "a black sheep that has to be sacrificed" in this case, without accusing anyone else of the murder.