The pilot who shot down a Russian fighter jet over Egypt last month was a Russian airman with a criminal history.
In October, a Russian pilot shot down an Egyptian military helicopter and killed two Russian servicemen.
Both pilots were shot down by Egyptian security forces and the Russians were taken into custody.
Russia’s Investigative Committee said they had no reason to believe the pilots were affiliated with a foreign terrorist group.
The Investigative Committee, the successor to the Soviet-era KGB, has been under pressure for years to crack down on Russian human rights abuses, especially in the wake of Russia’s annexation of Crimea and its aggression in eastern Ukraine.
The Russian military has been conducting operations in Syria in support of President Bashar al-Assad.
Russia is fighting against a U.S.-backed rebel alliance called the Free Syrian Army.
The Kremlin has been accused of violating human rights by the U.N. Human Rights Council and has faced calls to resign from some U.K. politicians.
In July, the Russian Foreign Ministry issued a rare public statement accusing the United States of violating international law by providing military aid to rebels in Syria.