Born to middle class parents in Daghestan, he became politically involved when he was a student at Moscow University, from which he was excluded.

He was a member of Georgi Plekhanov’s Yedinstvo group,[1] when he met Lenin in St Petersburg in December 1905 and joined the Bolsheviks.

Leon Trotsky, who described Alexinsky as a "shrieking orator and passionate lover of intrigue" alleged that he made a practice of accusing opponents of the war of being paid German agents, and was expelled from the Paris Association of Foreign Journalists as a "dishonest slanderer".

[5] He returned to Russia in 1917, after the February revolution, and in July produced documents to support his contention that Lenin was a German agent.

Alexinsky offered to sell the Soviet government, and then Columbia University, what he claimed were Lenin's letters to Elizabeth K., adding the new detail that she was his wife.