The man is thought to be Medhanie Yedhego Mered, a 35-year-old accused of shipping thousands of people to Europe and sending some to their deaths in the Mediterranean.
But within hours of his extradition to Italy on June 6th, reports emerged claiming that he was the victim of a case of mistaken identity.
Family and friends of the man pictured arriving in Rome claimed he was Mered Tesfamariam, a refugee. Tesfamariam also told investigators on Friday that he is not the man they want.
Italian and British authorities, which assisted Italy in the migrant trafficking probe, said they were investigating the claims.
The Palermo judge ruled on Tuesday that the man in custody must remain in jail as there is no evidence to suggest that he isn't Mered, dubbed 'the general' for his control over a vast area and number of 'troops', and described as "cynical and unscrupulous".
Meanwhile, prosecutors have said that while the man in custody may not be Mered, they believe he is involved in human trafficking. He has also admitted to making calls to Libyan people smugglers, prosecutor Maurizio Scalia said on Friday.