Moscow, Russia (CNN) She was shot twice in the chest, once in the shoulder, then once in the head at point blank range -- a classic sign of a professional hit.

Forensic teams who examined the body of Anna Politkovskaya, one of Russia's most prominent journalists and Kremlin critics, say the first two shots struck near her heart and were fatal.

The assassin, who had been waiting for her return from a shopping trip, used a pistol with a silencer attached.

For several minutes, her body lay undetected, slumped in the elevator of her Moscow apartment block before neighbors raised the alarm.

Justice has never been done

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In the ten years since this brutal murder, linked to her candid and fearless reporting of the conflict and human rights abuses in Chechnya, there have been numerous arrests, two trials and five convictions, including of three Chechen brothers.

But former colleagues say justice has never really been done.

"Absolutely no criminal investigation is taking place to find the person who ordered the killing," says Dmitry Muratov, editor of Novaya Gazeta, the independent Russian-language newspaper where Politkovskaya was a investigative reporter.

"The state should take responsibility and do everything it can to find who ordered this huge political killing," he told CNN.

But the Kremlin -- which denies any connection with the killing -- has a poor record when it comes to solving political murders, especially when investigations point to a Chechen connection.

Accused of gross abuses

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Chechnya lies in Russia's troubled Caucasus region, and was ravaged by two brutal wars in the 1990s between government forces and separatist rebels.

It's led by Ramzan Kadyrov, appointed Chechen president by the Kremlin in 2007 to control the republic.

Human Rights groups accuse security forces under his control of gross abuses, including torture and forced disappearances.

And now another trial is putting the spotlight back on Chechnya. In a courthouse in central Moscow five Chechen men stand accused of accepting cash to kill a leading Russian opposition figure in 2014.

'True Russian patriot'

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Boris Nemtsov, also a persistent critic of the Russian President, Vladimir Putin, was walking home late at night from a restaurant with his Ukrainian girlfriend when he was shot four times in the back.

The couple were on a bridge near the walls of the Kremlin when the assassin pulled up in a car and opened fired.

Police say the alleged trigger man, now on trial, was Zaur Dadayev, a former member of an elite Chechen military unit, loyal to Kadyrov and under his command.

After his arrest, the Chechen leader spoke strongly in Dadayev's defence, calling him "a true Russian patriot."

"If the court finds Dadayev guilty then by killing a person he has committed a grave crime," Kadyrov wrote on his Instagram page.

"But I want to note that he could not do anything that was against Russia, for which he has risked his own life for many years," the Chechen leader added.

Shrine to Politkovskaya

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At the Moscow headquarters of Novaya Gazeta, Anna Politkovskaya's old work space is untouched, left as a shrine to the murdered journalist.

A portrait hangs on the wall and fresh flowers adorn her desk.

But her colleagues say there is little hope those who ordered her killing, or those of Boris Nemtsov, will be held to account.

"We can catch the killers, we can catch the people who organize the killings," says Dmitry Muratov.

"But for the Russian justice system, the people who order them are inaccessible or they have immunity," he added.