Butler headed gang that terrorised US socialite's family

Anne Bass was victim of a terrifying raid led by Emanuel Nicolescu (pictured) (AP)

The plot might have been plucked from a crime novel: a wealthy US socialite and her boyfriend were tied up by an armed gang, injected with a "lethal virus," and told that, without help, they would be dead within 24 hours.

Only one thing could save them: an antidote carried by their masked attackers that would be administered after an $8.5m (£5.31m) ransom was paid.

Yesterday, the story ended in the old-fashioned way: with a jury in Connecticut, where the attempted heist was staged, deciding the butler did it.

Emanuel Nicolescu, ex-manservant of wealthy philanthropist Anne H Bass, was found guilty of leading a gang of three men who carried out the home invasion in 2007. His convictions, for extortion, conspiracy, and possession of a stolen vehicle mean he faces up to 50 years in prison.

Earlier, the court had heard how three men broke into the home that Ms Bass, the 70-year-old ex-wife of oil billionaire Sid Bass, shared with her boyfriend, Julian Lethbridge, shortly after 11pm. They brandished knives and howled what she described as "war cries."

The couple were led to a bathroom and blindfolded. Then their attackers "theatrically" donned latex gloves, and used syringes to inject "a very virulent virus" into their shoulders.

"When the symptoms appear, it's almost certain to be fatal," the gang's leader told them. "We want $8.5m. If you don't produce it, you will die."

Ms Bass, who is worth around $100m, said she didn't keep a large amount of cash at home, and said her three-year-old grandson was asleep in the house.

Five hours into the ordeal, the gang decided she really could not pay their ransom, and became concerned that staff would arrive for their morning shifts at the sprawling house, on a 100-acre estate near Hartford.

After a noisy debate, apparently in Romanian, they gave the hostages a drink, which they claimed was the "antidote," and which made the hostages fall asleep. The attackers then fled in a stolen Jeep.

Police later established the "deadly virus" was an antifungal found in athlete's foot treatments and the "antidote" was a sleep medication. Nicolescu was arrested after his DNA was found in the stolen Jeep. CCTV footage appeared to show him dumping it outside a Home Depot store in New York, several hours after the crime was committed.

The butler had been sacked from his $70,000-a-year job just over a year before the raid, for borrowing a vehicle without permission and crashing it.

His alleged accomplices are still at large, having fled overseas. Nicolescu gave no evidence, but a lawyer said he was "devastated by the verdict," maintains his innocence, and will appeal.