Ukrainian authorities also announced the arrest of 12 former riot police officers identified as government snipers who shot protesters in February.
They said dozens of other police and security personnel involved in the killings have fled to Russian-occupied Crimea.
The FSB and Russia's defence ministry also shipped five tonnes of grenades and other explosives to Ukrainian security forces, which used them against protesters, officials said.
Officials said hired civilian goons were also involved in killings of protesters and a journalist.
UPDATE: Ukrainian military analyst Dmitry Tymchuk said today on his Facebook page (translated here) that Beseda is a colonel-general who commands FSB intelligence operations against ex-Soviet republics. His role doesn't involve embassy security.
Tymchuk said sources informed him Beseda arrived in Kyiv Feb. 20 with a delegation of seven FSB officers.
In addition, Tymchuk names 20 other members of the FSB and other Russian intelligence agencies, half of them ranked lieutenant-colonel or above, who he says were already present in Kyiv at the time.
Footage Best Documenting Shootings
But the footage I think best documents the bloodbath remains this pair of videos showing heavily armed police with sniper rifles going into action -- as well as a 41-minute protesters' POV showing numerous unarmed protesters and medics getting shot, some while withdrawing.
The story cited these documents from Hennadiy Moskal, a Ukrainian parliament member and former deputy chair of Ukraine's SBU security service.