Rakhat Aliyev was propelled to power in 1983 when he married the daughter of Nursultan Nazarbayev, who was a powerful figure in the Communist Party before becoming the country’s first and only president post-independence.

He was appointed first deputy chairman of the National Security Committee and Kazakhstan’s first deputy foreign minister.

He went on to serve as deputy head of the Kazakh secret service, which is the post-independence reincarnation of the Soviet-era KGB.

Mr Aliyev claims he intended to reform the service but his critics have accused him of using his clout to secretly take over private companies for financial gain, often by threatening violence.

Over the years he built a sugar and media empire that made him a multi-millionaire.

But things started to go wrong in 2007, when he fell out with his powerful father-in-law after declaring himself a presidential candidate.

At around the same time, Mr Nazarbayev signed constitutional amendments effectively making him a president for life.

But these were only the final outcome of a dispute that was bubbling under the surface.

In February 2007, Mr Aliyev was appointed Kazakh Ambassador to Austria and Permanent Representative to the OSCE, shortly after he became embroiled in a controversy over the disappearance of two former executives of a Kazakh bank, which was part-owned by Mr Aliyev at the time.

The two bank managers from Nurbank were kidnapped and their bodies were found in May, 2011, when the dispute between the two men blew over.

Within days, the Kazakh government formally asked Austria to arrest Mr Aliyev for kidnapping and extradite him to Kazakhstan. His diplomatic immunity was withdrawn.

A month later, Mr Nazarbayev said his eldest daughter, Dariga, had divorced Aliyev,which effectively locked him out of the corridors of wealth and power in energy-rich Kazakhstan.

In August 2007, a Vienna court rejected a request from Kazakhstan to extradite Mr Aliyev on grounds he would not be given a fair trial in his home country.

In January 2008, Mr Aliyev was sentenced in absentia to 20 years’ imprisonment in a high security prison for the abduction of the bank managers. Two months later, he was convicted for preparing a coup d’etat and sentenced to another 20 years’ imprisonment.

He strenuously denies involvement in both cases, arguing they were orchestrated by the Kazakh government which had acted in the same way with other dissenters.

But the allegations of his former father-in-law are not the only ones dogging the 50-year-old. Two bodyguards of former Kazakh Prime Minister Akezhan Kazageldin have accused him of torturing them to extract statements that would frame their former boss.

Things started to go wrong in 2007, when he fell out with his powerful father-in-law

Mr Kazageldin, who is now in opposition, has pursued Mr Aliyev to get him to answer to criminal charges in Austria and Malta. However, these bids have failed.

Last May, Maltese courts turned down the former Kazakh Prime Minister’s attempt to force a police investigation for crimes against humanity, saying they had no jurisdiction.

In recent years, Mr Aliyev has faced several kidnap and assassination attempts, some of them well publicised.

In 2010, the Austrian secret service managed to foil a plot to kill him. The would-be murder weapon was traced to the Kazakh secret service. He moved to Malta shortly afterwards.

Mr Nazarbayev is accused by the Human Rights Foundation of having created a “post-modern dictatorship” that has looted the country of tens of billions of dollars through personal enrichment.

In his book The Godfather-in-Law (reprinted this year by Progress Press), Mr Aliyev says “the despot declared me his enemy when I decided I could no longer play along with him”.