Russians commemorated Thursday the killing of investigative journalist Anna Politkovskaya 15 years ago on President Vladimir Putin's birthday, while her newspaper warned time had run out to punish the masterminds of the murder.

Politkovskaya, a fierce critic of Putin and the Kremlin's wars in Chechnya, was shot dead on October 7, 2006, in the entrance hall of her apartment block in central Moscow. She was 48 years old.

Falling on Putin's birthday, the killing of a top investigative reporter -- who worked for Russia's leading independent newspaper Novaya Gazeta and contributed to Western publications including The Guardian -- sent shockwaves around the world.

But 15 years on, investigators have yet to say who was behind the apparent contract killing.

Anna Politkovskaya, a fierce critic of Putin and the Kremlin's brutal wars in Chechnya, was gunned down on October 7, 2006
Anna Politkovskaya, a fierce critic of Putin and the Kremlin's brutal wars in Chechnya, was gunned down on October 7, 2006 AFP / MAXIM MARMUR

"Neither I nor Novaya Gazeta have a final understanding of who ordered" the hit, her son Ilya Politkovsky, 42, told AFP on Thursday.

Novaya Gazeta editors say the authorities have no real interest in pursuing the investigation any further for political reasons, and on Thursday the statute of limitations on the crime expired.

But chief editor Dmitry Muratov told AFP that the newspaper had received a letter from the Investigative Committee, which probes major crimes in Russia, saying that the investigation would continue.

Still, Muratov said he was far from satisfied and not sure if the letter was merely a "bureaucratic trick."

The killing of a top investigative reporter -- who worked for Russia's leading independent newspaper Novaya Gazeta and contributed to Western publications including the Guardian -- sent shockwaves around the world
The killing of a top investigative reporter -- who worked for Russia's leading independent newspaper Novaya Gazeta and contributed to Western publications including the Guardian -- sent shockwaves around the world AFP / STAN HONDA

Novaya Gazeta has for years conducted its own investigation, but even its staff have not reached a united opinion on the identity of the murder's architects.

"The political leadership knows the name of the mastermind," deputy editor Sergei Sokolov told reporters.

Russians commemorate the killing of journalist Anna Politkovskaya 15 years ago
Russians commemorate the killing of journalist Anna Politkovskaya 15 years ago AFPTV / Nikolay KORZHOV

"From the very first days no one has been looking for him."

The commemorative events at Novaya Gazeta's editorial offices in Moscow came amid an unprecedented crackdown on the opposition and independent media, with authorities imprisoning Russia's top opposition politician Alexei Navalny.

Politkovskaya's son said his mother would not have been surprised by the current crackdown had she been alive.

"Much of what she wrote turned out to be a prophecy," Politkovsky said.

Politkovskaya's office has been turned into a small museum in her memory
Politkovskaya's office has been turned into a small museum in her memory AFP / Natalia KOLESNIKOVA

Thomas de Waal, a senior fellow at Carnegie Europe, put it more bluntly.

"Her fears have been realized. Free journalism is shut down and a veil of darkness has covered Chechnya for 15 years," he tweeted.

Politkovskaya's office has been turned into a small museum in her memory, which was unveiled in the presence of foreign diplomats Thursday.

The room features a desk, an old computer, and the murdered reporter's glasses perched on a copy of Russia's criminal code.

Putin's spokesman said it was "very difficult" to investigate contract killings.

"We would all of course like for the instigators of this crime -- both who ordered and executed it -- to be punished," Dmitry Peskov told reporters.

Asked if the Kremlin would be in favour of extending the statute of limitations for Politkovskaya's murder, Peskov said that the "inevitability of punishment" for such crimes was paramount.

In 2014, a court sentenced two men to life in prison for Politkovskaya's killing and handed lengthy prison terms to three others involved.

Lom-Ali Gaitukayev, a Chechen man who was found guilty of organising the hit, died in 2017 in a penal colony where he was serving a life sentence.

In 2018, the European Court of Human Rights condemned Russia for failing to take adequate steps to find those who ordered Politkovskaya to be killed.

Judges concluded that Russia should have explored possibilities that the crime was ordered by "agents of Russia's FSB domestic secret service or of the administration of the Chechen Republic".

Co-founded by former Soviet leader Mikhail Gorbachev in 1993, Novaya Gazeta is one of the few media outlets left voicing criticism of Putin, who turned 69 on Thursday.

Since 2000, six of the newspaper's journalists and contributors have been killed in connection with their work.