LONDON — When the Dutch police arrested a man last week on suspicion of being a fugitive Sicilian Mafia boss, at the request of the Italian authorities, the man’s Liverpool accent should have been a dead giveaway that they had collared the wrong person.
The 54-year-old British man, identified only as Mark L., had traveled to the Netherlands from Liverpool to attend a Formula One car race, the Dutch Grand Prix, in Zandvoort on Sept. 5. He was having dinner with his son at a restaurant in The Hague last Wednesday, when according to several local news media reports, armed police officers arrested him, believing him to be Matteo Messina Denaro, a mobster who has been on Italy’s wanted list since 1993.
Blindfolded, Mark L. was then transferred to a maximum-security prison, where he was held in isolation.
The following day, Leon van Kleef, a criminal defense lawyer in Amsterdam, was approached by local police officers, who said a man they suspected of being a Mafia boss and had arrested had specifically asked for him to be his legal representative.
A quick internet search by Mr. van Kleef’s colleague revealed who Mr. Messina Denaro was: a Sicilian mobster known to have killed police officers and prosecutors. He is also wanted for car bombings that killed dozens of people in the early 1990s.
“I asked myself, ‘Why would this guy ask for me, and how does he know my name?’” Mr. van Kleef said.
Intrigued, Mr. van Kleef visited the man in prison and recognized him — not as the Mafia boss he had seen on the internet, but as a man from Liverpool he had met some 15 years ago when he had delivered some clothing for a friend who was on trial in the Netherlands.
“He is really Liverpudlian, and not slightly,” said Mr. van Kleef, referring to Mark L.’s strong accent and deep family roots in Liverpool — not Sicily.
It was not until Saturday that Mr. van Kleef received word from the police that his client was to be released after it was determined that he was not in fact an Italian mobster.
“The man arrested in a restaurant in The Hague last Wednesday is not the man Italy is looking for,” the public prosecution department said in a statement on Saturday.
According to Mr. van Kleef, Mark L.’s lawyer, an Italian police officer had seen a picture of his client and had concluded that he was the fugitive Mr. Messina Denaro. The Italian authorities then notified the Dutch authorities, who arrested Mark L. with a European arrest warrant issued by the Italian authorities.
But, he said, “there is no similarity whatsoever between the photo that is known to public sources of Denaro, and the recent photo of my client.” He added: “They don’t even know if Denaro is alive, if he’s had facial surgery.”
Italian media reports suggested that prosecutors in the northern Italian town of Trento had pursued the case, and did not consult investigators in the Sicilian town of Palermo, who have long been chasing Mr. Messina Denaro.
However, Federico Cafiero De Raho, Italy’s chief anti-mafia prosecutor, defended officials in Trento, without going into the details of the case. “They operated in the correct way,” he said in a statement.
The prosecutor’s office in Trento did not respond to a request for comment.
Known as the “boss of all bosses,” Mr. Messina Denaro’s identity and whereabouts have been largely unknown since he went missing from his hometown in western Sicily in 1993. Investigators believe that he no longer lives in Sicily but travels across Europe, where there have been frequent but unsubstantiated sightings of the mobster.
According to Lirio Abbate, a Sicilian journalist who wrote a book about Mr. Messina Denaro last year, the Mafia boss remains highly respected by his associates, his business partners and even his many lovers, many of whom have been jailed and had their assets frozen by the police but have not betrayed him.
“Being hunted for so long has augmented his myth,” Mr. Abbate said.
The only pictures available of Mr. Messina Denaro are from a family album and were taken in the 1990s. But since publishing the book and appearing in a Netflix TV series, “World’s Most Wanted,” Mr. Abbate said he had received hundreds of unsubstantiated pictures from people who believe to have seen Mr. Messina Denaro across the globe, including police officers.
“Most people mean well, but it is difficult even for investigators who have tried to track him down for decades,” Mr. Abbate said. “He probably no longer even sees people. He sends letters and communicates without taking any risks. He is a professional in hiding.”