The father of the Italian sisters, who were acquitted of defrauding Nigella Lawson, has been arrested on charges of extortion during a raid on mafia mobsters in Milan.
Michele Grillo was one of 10 people arrested by Italian police on accusations of involvement in protection rackets and having links to the notorious 'Ndrangheta mafia, which is based in Calabria, where he originally comes from.
It was revealed last month that 66-year-old Mr Grillo was jailed for 15 years for his role in the kidnapping of an Italian fashion designer's sister in the 1980s. Tullia Kauten was held for four months in 1981 and only released after the payment of a ransom of €400,000.
Mr Grillo claimed recently that he had left his criminal past behind, establishing himself as a respectable businessman and setting up a trucking business in Milan.
"I was sent down when I was young. I was hanging around with some ugly company and was coerced into the kidnapping.
"But after prison I was a changed man. I have paid my debt to society," Mr Grillo said.
But his links to organised crime apparently did not go away.
According to a 200-page file compiled by police in Milan, Mr Grillo has links to the 'Ndrangheta clan that operates in and around Milan.
He was arrested on suspicion of being involved with the Barbaro-Papalia clan, a branch of the Calabrian mob.
Prosecutors allege that he is the right-hand man of Agostino Catanzariti, who was also arrested and is alleged to be the ring-leader of the clan in Milan.
The clan allegedly extorted protection money from businesses in the city, including night clubs, and also sold drugs.
"The link between business owners and the 'Ndrangheta goes back a decade with a sort of 'insurance' that was periodically renewed," said Paolo Storari, a prosecutor in charge of the investigation.
The clan has its roots in the poverty-stricken town of Plati in the southern region of Calabria, where the Grillo sisters -- Elisabetta (41) and Francesca (35) -- grew up before moving to the UK and eventually finding work with Ms Lawson, the celebrity chef.
Mr Grillo's arrest comes two weeks after his daughters were found not guilty of defrauding Ms Lawson and her then-husband, Charles Saatchi, of £685,000 (€829,000) through lavish spending on credit cards.
They alleged that Ms Lawson allowed them to spend freely on holidays abroad, jewellery and designer clothes in return for keeping quiet about her use of cocaine.
The "domestic goddess" admitted during the trial that she took cocaine with her late husband John Diamond when he found that he had terminal cancer, and in 2010 when she said she was being "subjected to intimate terrorism" by Mr Saatchi.