The 48-year-old Politkovskaya, who was sharply critical of the then president Vladimir Putin and his strongman policies in the volatile North Caucasus, was shot dead in broad daylight in her apartment building in central Moscow on October 7, 2006.

In a dark twist of fate, her death coincided with — some said was timed for — the birthday of Putin, who three days after the murder dismissed her ability to influence politics in Russia as “extremely insignificant.”

An investigation into her killing has been long, complicated and tortuous.

In a major development in the long-running case, Russia last month charged a former senior police officer, Dmitry Pavlyuchenkov, with helping organise the murder in exchange for cash but authorities have so far failed to secure any convictions.

But the biggest disappointment, say Politkovskaya’s relatives and

supporters, is that half a decade after her murder it still remains unclear who wanted her dead.

“We still have no information about the person who ordered the killing, about the motive,” Politkovskaya’s son Ilya told AFP.

He cautiously praised the investigation, which was reopened after a 2009 court decision to acquit two suspects was overturned.

Still, he said, “much more could have been done. I had thought it would have been resolved in about three years.”

Her colleagues and rights campaigners say the loss of arguably Russia’s most prominent opposition reporter still loomed large and no one had so far emerged to fill her shoes.

“Some time ago I had the idea that journalists and the human rights community can sort of become a collective Politkovskaya,” veteran rights campaigner Svetlana Gannushkina told AFP. “That didn’t happen.”

“It’s an irreplaceable loss,” she said.

A star reporter of the opposition newspaper Novaya Gazeta, Politkovskaya earned wide acclaim — and made many enemies — for her post-war reporting from Chechnya in the early 2000s, meticulously documenting torture, suffering and the heavy-handed tactics of Russian troops in the Caucasus.

Never one to mince words, Politkovskaya frequently spoke out publicly, once calling Putin a “little grey man” and branding the Chechen leader Ramzan Kadyrov a “liar.”

She won international prizes for her reports accusing Putin, who is now Russia’s prime minister, of using the Chechen conflict to strangle democracy in Russia. Her pieces frequently featured stories from Chechen refugees, Russian soldiers, and relatives of missing persons.

She investigated several cases of torture in the Caucasus which subsequently made their way to court, an extremely rare occurrence for a region.

Sergei Lapin, a policeman serving in Chechnya, was sentenced to over 10 years in jail for kidnapping and torturing Chechen Zelimkhan Murdalov in an effort to force him to admit being a militant in 2001.

“She had so much inner energy that she translated into her stories,” said Gannushkina, co-founder of leading human rights group Memorial nominated for the 2011 Nobel Peace Prize. “She knew how to hit a raw nerve.”

Politkovskaya also did not shy away from interviewing Caucasus militants, earning herself a controversial reputation among the Moscow elites. Many accused her of condoning separatism.

Novaya Gazeta editor Dmitry Muratov said Politkovskaya had been proved right in predicting a recent spike in nationalist sentiments fuelled by the Kremlin’s misguided policies in the North Caucasus.

Her murder has also changed the way reporters do their jobs, especially in the restive North Caucasus, he said, adding that he has since tried to curb jounalists’ trips to the region over safety concerns.

“The Caucasus news image is not complete now due to both editorial decisions as well as self-censorship,” Muratov told AFP.

“If the goal of the murder was to limit this information, that goal has been accomplished,” he said, adding that he expects the new trial to start no earlier than six months from now.

Muratov, whose newspaper is conducting a parallel investigation into their colleague’s killing, said whether or not Russia finds the mastermind will in many ways depend on the political situation in Russia, to be shaped by Putin’s imminent return to the Kremlin in March polls.

In August, investigators said they had information on the supposed mastermind of the killing, who has never been identified.

If there is one thing Putin can do to greatly help the matter, it is saying sorry for his callous remarks about Politkovskaya, said Muratov.

“I think Putin should apologise,” he said. “If saving people’s lives is insignificant, then human life is worthless in this country.”