An unidentified attacker shot Nemtsov four times in central Moscow, a law enforcement source told Russia’s Interfax news agency.
The Internal Affairs Ministry confirmed the killing.
“[We] confirm that the man was killed in central Moscow, documents for the name Boris Efimovich Nemtsov have been found,” Interfax quoted the ministry’s press service as saying.
Nemtsov was shot near the Kremlin while walking with a woman, according to Russian-language news website Meduza. “Several people” got out of a car and shot him, Meduza said.
He was shot in the back with a pistol from a white car which fled the scene, Interfax’s source said.
The assassination came on the eve of a major opposition rally in Moscow.
Nemtsov, 55, served as first deputy prime minister under the late president Boris Yeltsin in the 1990s.
He earned a reputation as an economic reformer while governor of one of Russia’s biggest cities, Nizhny Novgorod.
Falling out of favour with Yeltsin’s successor, Vladimir Putin, Nemtsov was an outspoken opposition politician.
Since 2012, heled the pro-business party RPR-Parnas (Republican Party of Russia — People’s Freedom Party).
Earlier this month, Nemtsov told Sobesednik news website he feared for his own life.
“I’m afraid Putin will kill me,” he said on February 10.
I believe that he was the one who unleashed the war in Ukraine,” he said. “I couldn’t dislike him more.”
Earlier, Nemtsov’s colleague confirmed his death.
“Unfortunately, I’m currently looking at the body of Nemtsov on the Zamoskvoretskiy bridge,” said Ilya Yashin, a fellow member of RPR-Parnas. “I see the body, and a lot of police.”
Putin was “immediately informed” about Nemtsov’s assassination, presidential press secretary Dmitry Peskov said.
“Putin has stressed that this brutal murder has all [the] signs of a contract murder and is extremely provocative,” Peskov said.
“The president has expressed his deep condolences to the family of tragically deceased Nemtsov,” he added.Police have dubbed the operation to catch the killers ‘Interception.’