A court in Russia has sentenced five men convicted of murdering opposition leader Boris Nemtsov to 20 years in jail.

Of the convicts, Zaur Dadayev, a soldier from southwestern Russia's predominantly Muslim republic of Chechnya, was handed the longest term on Thursday.

Four other men, also Chechens, were convicted for various roles in the murder which sent shockwaves throughout Russia's fragmented political opposition.

They were sentenced to between 11 and 19 years, state media reported.

The same court last month found the five men guilty of killing Nemtsov in 2015, but the late politician's allies said the investigation had been a cover-up and that the people who had ordered his killing remained at large.

READ OPINION: Boris Nemtsov's last walk

Nemtsov, a scathing critic of President Vladimir Putin, was murdered days before he was expected to lead a major opposition march.

Murdered Kremlin critic Boris Nemtsov remembered at rally

His death also came before the release of a controversial report implicating the Russian military in the conflict in Ukraine.

Dadayev reportedly confessed early in the investigation to killing Nemtsov for insulting Islam and Chechnya's leader, Ramzan Kadyrov, but later recanted his confession.

Al Jazeera's Andrew Simmons, reporting from Moscow, said the sentences do not resolve the case with Nemtsov's family insisting that the real perpetrators behind his murder are still on the loose. 

"The family of Nemtsov feels they may never know who was actually responsible for his killing," he said. 

Another man, Ruslan Mukhudinov, who was named as the mastermind behind the attack by Russian investigators, has not been found and is on an international wanted list. 

Thursday's sentencing also coincided with a statement by the Russian investigation team which said that the motivation for the contract killing was financial. 

"There were a lot of political aspects to this case that many people feel really haven’t been addressed," our correspondent said.

Watch Inside Story: Russian opposition - Critics or traitors?

Source: Al Jazeera and news agencies