A Malaysian private investigator who returned from self-exile vowing to lift the lid on a sensational scandal linked to the country's prime minister died suddenly on Friday, his lawyer said.
P. Balasubramaniam, 53, died of a heart attack in the capital Kuala Lumpur, less than a fortnight after suffering an initial attack that hospitalised him for a week, his lawyer Americk Sidhu told AFP.
Balasubramaniam was a key figure in a scandal linking Malaysian premier Najib Razak with a Mongolian woman's murder and alleged kickbacks in a 2002 submarine deal.
Americk said Balasubramaniam had complained of breathing difficulties and later died in a clinic.
Balasubramaniam, an ethnic Indian Malaysian citizen, returned from India last month, with media reports quoting him as saying he would expose the truth in the murky scandal.
His return came as Malaysia braces for hotly contested elections due within months, in which the opposition is seen as having its best chance ever to dethrone the long-ruling coalition now headed by Prime Minister Najib Razak.
Americk said Balasubramaniam had planned to campaign for the opposition.
The scandal revolves around a $1.1 billion purchase by Malaysia of two submarines from French arms giant DCNS, inked in 2002 when Najib was defence minister.
DCNS is alleged by the opposition to have paid kickbacks to top officials amounting to more than 114 million euros ($142 million) via a purported shell company linked to Abdul Razak Baginda, a former close associate of Najib's.
Balasubramaniam had said he was hired by Abdul Razak to investigate the latter's mistress Altantuya Shariibuu, a Mongolian translator. Abdul Razak alleged she was blackmailing him for a cut of the money.
In 2006 she was shot dead and her body was blown up with plastic explosives near Kuala Lumpur.
Two police bodyguards assigned to the prime minister's office have been convicted of the killing. The ruling is under appeal.
In 2008, Balasubramaniam implicated several government officials, including Najib, in the murder. He later recanted before doing yet another U-turn, saying he was being coerced to keep silent and fleeing to India.
Najib has denied knowing the Mongolian or having any knowledge of wrongdoing in the deal. Malaysian authorities have ignored calls to investigate.
But the affair was revived last year when French judges, acting on a complaint by a Malaysian rights group, launched a new probe that is still under way.
There have been no immediate claims of foul play in Balasubramaniam's death.
However, R. Sivarasa, a lawyer for Malaysia's opposition, said on Twitter the deceased's family was requesting a post-mortem examination.