A Formula 1 fan from Liverpool was arrested at gunpoint in the Netherlands after being mistaken for a mafia boss.
The 54-year-old, known only as Mark L, was blindfolded and led away by police in The Hague on Wednesday who thought they had captured Sicilian crime lord Matteo Messina Denaro, 59.
Mark L, who had attended the grand prix on 5 September, has now been freed, the Dutch Public Prosecutor's Office said.
Denaro is wanted over bombings in 1993 in which 10 were killed and 93 injured.
Mark L had been eating at a restaurant with his son when police burst in, carrying a European Arrest Warrant issued by the Italian authorities.
His lawyer Leon van Kleef said: "It's like a bad movie, a nightmare that my client has found himself in.
"Imagine one moment you are having a bite to eat and the next you are sat in a maximum-security Dutch prison."
A spokeswoman for the Public Prosecutor's Office said Mark L "stated he was an English citizen and not the person claimed by Italy".
She added: "The outcome of the investigation, which was conducted via an accelerated procedure, turned out to be negative.
"The public prosecutor then issued an immediate release order at the beginning of the evening."
Denaro is Italy's most wanted mafioso who once boasted he could "fill a cemetery" with his victims.
He is also known as Diabolik - a nickname he took from an uncatchable thief in a comic book - and is seen as the successor to two jailed Mafia godfathers.