Russia Ordered a Killing That Made No Sense. Then the Assassin Started Talking.

The target lived on the sixth floor of a cheerless, salmon-colored building on Vidinska Street, across from a thicket of weeping willows. Oleg Smorodinov found him there, rented a small apartment on the ground floor, and waited.

He had gotten the name from his two handlers in Moscow. They met at the Vienna Cafe, a few blocks from the headquarters of Russia’s domestic intelligence agency, and handed him a list of six people in Ukraine. Find them, they told Mr. Smorodinov, and he set off. He was already boasting to friends that he was a spy.

Each person on the list was assigned a code name related to flowers. One was ‘briar.’ Another was ‘buttercup.’ The target, a man named Ivan Mamchur, was called ‘rose.’ To Mr. Smorodinov, he was a nobody, an electrician who worked at the local jail. To the handlers in Moscow, though, he was significant.

“Drenched in blood up to his elbows,” they told him.

The surveillance was uneventful. At 7 each morning, Mr. Mamchur left his wife and daughter, rode his bicycle to work, and returned each evening at 6. “Like clockwork,” Mr. Smorodinov recalled. In his idle hours, Mr. Smorodinov drank beer in the parking lot where an old woman kept watch on a clowder of cats.