ROME -- Italian police have arrested a Moroccan man on a Tunisian arrest warrant accusing him of helping organize and execute the March 18 attack on Tunisia's Bardo museum that left 22 people dead, authorities said Wednesday.
Touil Abdelmajid was arrested Tuesday evening at the home of his mother in Gaggiano, near Milan, anti-terrorism investigator Bruno Megale told a news conference.
The accusations listed in the Tunisian arrest warrant include premeditated murder, conspiracy to commit attacks against the internal security of the state, belonging to a terrorist group and recruiting and training others to commit terrorist attacks, Megale said.
"He was wanted internationally for co-participation in, planning and executing the March 18 attack on the Bardo museum in Tunis," Megale said.
The Islamic State of Iraq and Syria (ISIS) claimed responsibility for attacking the Bardo, Tunisia's leading historical museum, which has a trove of Roman mosaics.
Gunmen opened fire on tourists getting out of buses and then entered the museum, apparently unimpeded, and fired on more tourists inside. Two gunmen were killed in a shootout with police. Four Italians were among the dead.
A number of people have been arrested in connection with the attack, but the Tunisian Interior Ministry has said the mastermind of the attack is still at large.
Megale said Abdelmajid had been unknown to Italian authorities except for an expulsion order issued by Sicilian authorities in February.
Police were able to identify him in part after his mother reported that her son's passport was missing immediately after the Bardo attack.
The February expulsion order led to another major worry for Italy; how Abdelmajid came to be in the country in they first place.
Police said Wednesday that the Moroccan arrived in Italy aboard a migrant boat a month before the attack and was ordered expelled, but it's not clear how or if he ever left.
Megale said only that Abdelmajid was identified in Porto Empedocle, Sicily, on Feb. 17 and was issued an expulsion order.
The news fueled criticism of Italy's migrant rescue operations by anti-immigrant politicians, who have warned that Islamic extremists could slip into Italy among the thousands of would-be refugees fleeing Libya aboard smugglers' boats.