Controversial claims: Perumal Balasubramaniam.
A former private detective at the centre of allegations swirling around the murder of a glamorous Mongolian socialite in Malaysia has died in Kuala Lumpur of a suspected heart attack.
Perumal Balasubramaniam, who is known as PI Bala, had returned to Malaysia early this year from self-imposed exile in India to campaign against the Barisan Nasional coalition led by prime minister Najib Razak that faces an election by mid-year.
Mr Bala, 53, had controversially claimed the 28 year-old socialite Altantuya Shaariibuu was sexually linked with Mr Najib before she was murdered in a patch of jungle in the Kuala Lumpur suburbs in 2006. Mr Najib strenuously denies the claim, saying he has sworn on the Koran he never met Ms Shaariibuu.
Murdered: Altantuya Shaariibuu.
Malaysia's opposition had planned for Mr Bala to play a major role during what is expected to be the tightest election campaign in Malaysia's history.
Investigations into the murder of Ms Shaariibuu raised allegations of high-level bribery, blackmail, betrayal and cover-up around Malaysia's $US2 billion purchase of two French-Spanish built Scorpene submarines in 2002 while Mr Najib was defence minister.
The government and Mr Najib deny any wrongdoing in the purchases.
Ms Shaariibuu worked as a translator in the latter stages of the deal negotiations.
Mr Bala made the claim about Mr Najib in a statutory declaration in July 2006 but recanted it the next day. Later he claimed he changed the statement because of threats to his family and that he was offered money to leave the country.
Two of Mr Najib's bodyguards were convicted in 2009 of the murder of Ms Shaariibuu, who had been dragged from a car, knocked unconscious and shot twice in the head as she begged for her life and apparently that of her unborn child.
The killers then wrapped her body in C4 explosives and blew her up.
The bodyguards are appealing the convictions.
Mr Bala told journalists when he returned to Malaysia in January he wanted to expose the truth about his involvement and knowledge of the case.
He attended a rally by the opposition People's Alliance last month but soon after was diagnosed with heart problems.
The claims by Mr Bala and others relating to the events of 2006 by well connected Kuala Lumpur businessman Deepak Jaikishan have not been reported in Malaysia's government-controlled mainstream media but have been hot issues on opposition and independent websites.
Meanwhile, officials of the Barisan Nasional held a marathon meeting at the weekend to prepare for the elections which Mr Najib is expected to call within weeks.
Malaysia's charismatic opposition leader Anwar Ibrahim has said he is confident of ousting the Barisan Nasional, which has ruled continuously since Malaysia gained its independence from Britain more than half a century ago. But most analysts predict the ruling parties will probably be returned with a reduced number of seats.