A report outlining the extent of Russia's military involvement in Ukraine, which was being prepared by Russian opposition leader Boris Nemtsov before his murder a few days ago, will be completed and published, opposition activists say.

Ilya Yashin, a prominent figure in the Russian opposition and a close ally of Nemtsov's, told the U.K.'s Times newspaper that evidence collected by Nemtsov, which the opposition leader alleges included the testimony of the parents of Russian soldiers killed fighting in Ukraine, was still available to the opposition.

“Nemtsov told me he was going to start work on a report entitled Putin and the War that would prove that Russian forces were present in Ukraine [and] took part in clashes with Ukrainian forces,” he said.

I have some ideas how to pick up the pieces of his report, but this is not something that can be done in a few days,” he added.

The details of Nemtsov's report were feared to have been lost, after Russian police seized the slain politician's laptop, which was believed to contain the only copy of the evidence he had compiled, and sealed his apartment.

Nemtsov's killing on Feb. 27 prompted accusations from Ukrainian President Petro Poroshenko that he was murdered in order to prevent his report on Russian involvement in the war in Ukraine. Moscow has vehemently denied such claims.

Nemtsov was shot four times in the back on a Moscow bridge, near to the Kremlin. He died shortly afterward.

The results of a poll, published Wednesday by independent Moscow-based pollster the Levada Center, and reported by the Moscow Times, found that a majority of Russians believe their government when it says it has not sent troops to Ukraine.

The poll revealed that 53 percent of respondents believe that their country has not deployed any forces to Ukraine, while one quarter of those surveyed believe that it has, the paper reported.

Russian President Vladimir Putin called on the country's security services Wednesday to do more to prevent political murders in the country. Investigators have reportedly identified several suspects in the case.