Russian investigators have identified a man who opened fire on the Moscow headquarters of the Federal Security Service (FSB) as Yevgeny Manyurov, a 39-year-old former security guard.
Russia's Investigative Committee made the announcement on December 20 after searching his home earlier that day and questioning his neighbors.
Manyurov, who was shot dead during the attack, opened fire on the FSB's main building in Moscow on December 19, killing one FSB employee on the spot and wounding five others, including one civilian.
The Committee's spokeswoman, Svetlana Petrenko, told reporters on December 20 that a second FSB employee who had been seriously wounded in the attack died later from his wounds.
"One FSB officer was killed and another one died later in hospital," Petrenko said.
Investigators are working at the scene of the attack and the criminal case has been forwarded to the the investigative committee's central department for further investigation.
The FSB is the main successor agency to the Soviet-era KGB.
The shooter's motives remain unclear.
The attack occurred at around the same time when President Vladimir Putin, a former KGB officer, delivered a speech at a Kremlin concert marking the Day of Russia's Security Services. which falls on December 20.
Some Russian media, citing unnamed sources, said that Manyurov used to work as a security guard for various private companies and was a member of a rifle club and owned a small arsenal of shotguns and rifles.
Russia Names Suspect Behind Moscow Shooting, Says Death Toll Now Two