Tunisian Anis Hannachi was arrested in Ferrara on Saturday.
Police in Italy have arrested the brother of a Tunisian man who stabbed to death two women in the French city of Marseille earlier this month. Ahmed Hannachi reportedly shouted "Allahu Akbar" as he stabbed the women. While admitting she had not seen him for more than two years, she said the murder of the two women was more likely a robbery gone wrong because he was a drug user and always in need of cash.
The Islamic State group has claimed responsibility for Hanachi's attack, but French investigators have not yet found evidence linking him to the jihadist organisation.
An Italian anti-terrorism squad arrested 25-year-old Anis Hannachi in Ferrara, Italy, on Saturday evening on an worldwide warrant issued by France, a police statement said. He was not known to police as a radical Islamist, and was rejected at the border when he tried to enter Italy in 2014 because he was undocumented, Police Antiterrorism Director Lamberto Giannini told reporters at a televised news conference on Monday. The French authorities had notified Italy that he was probably in Italy on October 3 and on October 4 it was ascertained that he was in Liguria.
Another one of his brothers and a sister were detained in Tunisia late last week and had been questioned by anti-terror investigators there.
"They appeared before an investigating judge ... who made a decision to transfer the case to the National Guard" in the north-eastern city of Aouina.
He is accused of being complicit in his brother's attack and of participating in a terrorist organization.
His older brother, the 29-year-old Ahmed, was shot dead by a French soldier after killing the two women on October 1.
"Ahmed never showed any signs of radicalisation in Italy", Roberti said.
Tunisian security sources have said they suspect both Ahmed and Anour Hanachi of being "extremists".
The Marseille attacker's estranged wife told Italy's Corriere della Sera newspaper on Sunday that she did not believe Ahmed had become a radical Islamist.