A Mafia-associate-turned-informant is deathly afraid of an Ivy League-educated business partner who claims the mob rat cheated him on a land deal.

Now, canary Salvatore Lauria has filed a $5 million Manhattan suit claiming his ex-business partner became a wiseguy wannabe in his quest to nail him over the dough.

Seemingly “squeaky-clean’’ Wharton Law School graduate Jody Kriss “used mob tactics’’ — nearly getting him killed — to try to get his half of the $2.5 million payday, Lauria claims in his bombshell civil lawsuit, which was obtained by The Post.

For example, a vengeful Kriss disclosed sealed government information to a famous mob lawyer who represented the very people Lauria informed against, prompting a mob beatdown of Lauria, the court papers say.

In July 2012 a Mafioso “tracked down Lauria in a restaurant in Bay Ridge, Brooklyn . . . and beat Lauria in broad daylight, menacingly telling Lauria, “You’re dead. I’m going to kill you. You’re a rat. I did two years because of you,” the suit says.

Kriss, 36, of the Upper West Side, who worked with Lauria at the real-estate conglomerate the Bayrock Group, took on a mob persona, according to the papers.

Russian pals started calling him “Vor-ton,” a play on his alma mater Wharton,’’ the suit says. In Russia, mobsters are referred to as vor-in-laws, or thief-in-laws.

Kriss was so enamored of the criminal underworld that he also “would routinely ask to see Lauria’s court-mandated ankle monitor and referred to it as ‘federal jewelry,’ ” according to the papers.

Lauria, 51, turned federal informant in the 1990s to dodge a racketeering charge as part of a $40 million Wall Street pump-and-dump scheme.

A former Gambino and Genovese associate, his testimony helped put away the relatives of Carmine “the Snake’’ Persico and Sammy “Bull’’ Gravano.

Lauria began consulting for Bayrock, whose projects include the Trump Soho hotel/condominiums on Spring Street, with Kriss as the front man, the lawsuit says.

But Kriss grew furious when Lauria brokered an $85 million real-estate deal with the FL Group of Iceland in 2007 and took the entire $2.5 million commission, the lawsuit says.

“Our client is not a saint,” admitted Lauria’s lawyer, Michael Beys.

Kriss responded in a statement: “This is merely the latest in a string of increasingly desperate attempts to pressure me and other victims … to stop lawsuits they are losing. None of the bullying tactics will have any effect.”