Ukrainian police say they have new evidence to identify the culprits in the murder of renowned investigative journalist Pavel Sheremet.
The 44-year-old was killed by a car bomb explosion while driving in the Ukrainian capital, Kyiv, on 20 July 2016. His murder has not been solved.
But Ukraine's National Police said on Monday that they had received "documents and audio recordings" related to the case in December.
"Documents and audio recordings, the last of which is dated 2012, have already been made available to the investigation and are of interest in terms of identifying the perpetrators of the crime," the police said in a statement.
The authorities added that they have received permission to carry out investigations further in an unnamed European country, and are appealing for more information.
Five suspects, veterans of the war between Kyiv forces and pro-Russian separatists in eastern Ukraine, were arrested in December 2019 in connection with the killing. They have denied any wrongdoing and relatives of Pavel Sheremet have expressed doubt about their involvement in the murder.
In July, Ukraine's President Volodymyr Zelensky demanded that investigators provide "convincing and irrefutable evidence" of the suspects' involvement and called for the real instigators of this murder" to be unmasked.
Pavel Sheremet had been a harsh critic of the Russian, Belarusian and Ukrainian authorities. The journalist had worked for Belarusian national television before leaving the country due to a conflict with the authoritarian regime of President Alexander Lukashenko.
He had then settled in Russia, obtaining citizenship and working for two Russian public channels, before he moved closer to the country's opposition and resigned in 2014.
Sheremet then moved to Kyiv, where he continued to criticise Russian President Vladimir Putin, alongside the Ukrainian authorities.
Ukrainian police said that the new recordings were obtained with the help of the country's Foreign Intelligence Service.
"Fragments of information available to the investigation of the National Police have been published on the Internet," the statement said, "unidentified persons are discussing the murder of journalist Pavel Sheremet in published records."
"In particular, the option of poisoning with the use of toxic substances, as well as undermining, was emphasised."