A second Russian security officer has died after a gunman opened fire at the Federal Security Service (FSB) headquarters in Moscow on Thursday.
The FSB officer died of his wounds in hospital, the Investigative Committee (SK) said. The shooting with an assault rifle killed an officer at the scene.
The SK confirmed that a lone gunman, Yevgeny Manyurov, had attacked the HQ's entrance. A sniper shot him dead.
Five others were wounded when Manyurov opened fire, one of them a civilian.
The SK statement confirmed earlier media reports that Manyurov was aged 39 and had lived just outside Moscow. The motive for his attack remains unclear.
Russian media, quoting unnamed police investigators, described him as a loner and gun enthusiast. He lived in Podolsk, about 40km (25 miles) south of Moscow.
At the Kremlin, a couple of kilometres away, President Vladimir Putin was at a gala evening honouring the FSB.
The details about the gunman were reported by Russian government daily Rossiiskaya Gazeta on Friday.
The FSB headquarters - called the Lubyanka - used to house the Soviet KGB. The FSB is Russia's main domestic intelligence service.
'Islamic State-type slogans'
On Thursday night police searched Manyurov's flat, which he had shared with his mother, and they detained her for questioning.
Her son had worked as a security guard but lost his job recently and never had any visits from friends, Russian media quote her as saying. Police found five guns at the flat - legally registered and kept in a safe - along with a large quantity of ammunition.
Manyurov once trained as a lawyer and did some legal consulting work, reports say.
He was single and practised shooting regularly at a gun club, which was a passion for him, his mother is quoted as saying.
She also said she had heard him speaking English on the phone with some "Arabs", who had started calling him since he had lost his security job.
When he opened fire, Manyurov "was shouting slogans typical of Islamic State", the daily Kommersant reports. It says the information came from a security source, who quoted witnesses questioned by police.
Fatikh Manyurov, the gunman's father, gave more details to Russia's Telegram 112 news channel. His son had told him he was working as a security guard at a foreign embassy, he said. That has not been confirmed, however.
His son was "morose" and dreamt of becoming a "master of sport" in shooting, said Fatikh, who is separated from Yevgeny's mother. He said he had rarely spoken to his son.
The Russian daily Komsomolskaya Pravda interviewed a shooting instructor at the Dosaaf club where Yevgeny Manyurov practised and took part in at least two shooting competitions.
The instructor, Oleg Solovich, said Yevgeny Manyurov "was a poor shot". "To be a good shot you need to train for a few years. He practised at our club for about three months," he said.
"He socialised normally, but came to training sessions wearing a long black raincoat - a Parka - with a hood. We advised him to take off his coat during shooting sessions, but he said he felt comfortable in it," he said.
The shooting came just hours after President Putin's marathon annual press conference, which went on for more than four hours.
At the gala evening, in the Kremlin Palace, Mr Putin stressed the importance of "intensive" FSB work to fight terrorism.