He’s got a killer Napoleon complex.

A top professor chopped up his student-turned-lover and planned to commit suicide dressed as Napoleon Bonaparte — but was caught drunkenly trying to toss his victim’s arms in a river, authorities said.

St. Petersburg State University Professor Oleg Sokolov, 63 — Russia’s most famous Bonaparte re-enactor — had met his 24-year-old lover, Anastasia Yeshchenko, when she enrolled in one of his French history classes, police said.

The pair were soon sharing more than their passion for the Napoleonic era.

Their love affair became well-known on the St. Petersburg campus, with some students describing him to Agence France-Presse as a “freak’’ who dressed up as Napoleon during re-enactments while having her don the role of the French dictator’s wife, Josephine, and call him “Sire.”

But things between the pair had soured recently, with Yeshchenko moving out of their shared abode along the Moike River, cops say.

Sokolov allegedly flew into his murderous rage last week, when his former student criticized his two adult daughters during another argument at the apartment, according to the Washington Post.

The eccentric scholar — once awarded France’s highest accolade, the Légion d’Honneur — ended up shooting Yeshchenko with a sawed-off shotgun in the St. Petersburg pad on Thursday, authorities said.

The next day, he entertained friends there — while Yeshchenko’s body lay in another room behind a closed door, cops say.

After his guests left, Sokolov then hacked up Yeshchenko’s corpse — but he wasn’t fully up to the grisly task and started drinking alcohol because he was having trouble stomaching what he’d done, they allege.

Sokolov eventually stuffed her arms into a backpack and headed out the door, hoping to throw them into the river to begin disposing of her remains, according to authorities.

But at some point during the mission, the scholar tumbled into the icy drink and was forced to call out for help, they said.

A passing cabbie found the boozed-up, bumbling killer and called the police, cops said.

When cops arrived, Yeshchenko’s arms were discovered in Sokolov’s bag. Her head, legs and torso were found back at his home, along with a bloody saw, authorities said.

Sokolov quickly copped to his crime, according to authorities — adding to police that he planned to off himself with the kind of drama befitting his idol, the power-mad French emperor.

The professor said he wanted to kill himself in front of tourists at the landmark Peter and Paul Fortress in St. Petersburg while dressed as Napoleon.

Sokolov is fully cooperating with authorities because he is remorseful, his lawyer told AFP.

“He has admitted his guilt,” the lawyer, Alexander Pochuev, told the outlet.

Sokolov was being treated at a local hospital for hypothermia.

Yeshchenko was a graduate student at the university — Russian President Vladimir Putin’s alma mater — when she was killed, authorities say.

“She was quiet, sweet,’’ a friend told the Russian RIA Novosti news agency.

A university lecturer said, “What happened is simply monstrous.’’