Ukraine has accused both ousted pro-Kremlin president Viktor Yanukovych and Russian security agents of being responsible for unrest in Kiev in February that claimed nearly 90 lives.
Acting interior minister Arsen Avakov said Mr Yanukovych issued the "criminal order" to fire at the pro-EU protesters while agents from Russia's Federal Security Service (FSB) helped him plan and carry out the deadly assault.
"Yanukovych issued the criminal order ... to open fire against protesters on 18-20 February," Mr Avakov told reporters.
"FSB agents took part in both the planning and execution of the so-called anti-terrorist operation," he added.
Three months of at-times violent anti-government protests by supporters of closer European ties culminated in two days of carnage in Kiev that led to parliament's 22 February ouster of Mr Yanukovych and his Russian-backed government.
Nearly 20 people, most of them protesters, died of gunshot wounds during hours of street battles across central Kiev on the night of 18-19 February.
More than 60 people were killed on 20 February during battles that broke out on Kiev's central Independence Square in the morning and continued into late afternoon.
Many of those who died appeared to have been killed by snipers.
Russia has suggested that ultranationalists were the first to open fire against the police in an effort to spark a larger altercation that could then be blamed on Mr Yanukovych and his backers in the Kremlin.
Ukrainian prosecutors announced the arrest of 11 Ukrainian anti-riot police officers and their commander for their involvement in the unrest.