Former KGB agent-turned-whistle blower Alexander "Sasha" Litvinenko has the look of the mature celebrity chorister Aled Jones about him.

Cherubic, good-humoured and a doting husband and father, he's the last person you'd expect to die a gruesomely lingering death after being poisoned with a radioactive timebomb.

Yet in November 2007, a 43-year-old Litvinenko - who had fled Russia after exposing the criminal actions of the security service - fought a losing battle against the ravages of Polonium-210.

Documentary-maker Andrei Nekrasov, who interviewed the dissident spook at length before his death, has eschewed a quasi-police procedural of his friend's demise and put together a damning chronicle of the system that led to his assassination.

The picture he paints is not a pretty one. The story begins in the 1990s when Litivinenko was a respected operator in the Russian FSB, the successor to the Soviet era's ruthless KGB.

Lacking the morally vague - ie unaccountable - climate in which to operate, power crazed politicos serving under President Yeltsin engineered the Chechen war by staging a number of "terrorist' attacks which were actually the work of maverick FSB agents.

The result was a conveniently illegitimate regime where state-sponsored terrorism was the norm and the FSB operated as undercover wing of a Kremlin elite. All, that is, except for the likes of Litvinenko.

Nekrasov has amassed an impressive collection of TV footage of showing the FSB whistle-blowers turned on by the state and ostracised (and worse) for daring to speak the truth.

A rather scatter-gun approach also makes allegations that Putin - then a senior politician in St Petersburg - was up to his neck in a multi-million dollar scam that denied the city's starving citizens food.

This merely serves as a distraction from the damning indictment that a caviar-and-vodka-swilling, self-serving elite rule over a country where 50% are below the poverty line.

As murdered journalist Anna Politkovskaya points out, political life in contemporary Russia "is like falling into a cesspool".

Tim Evans