Updated

Egyptian authorities say a suspected Libyan militant will remain in custody for 15 days pending an investigation into a deadly attack in the country's Western Desert.

A statement from prosecutors Friday says the Libyan and 14 other suspected militants face terror-related charges, including killing police forces and joining a terrorist group.

Sixteen police were killed in the Oct. 20 attack, according to an official tally issued by the Interior Ministry. Security officials have told journalists that dozens more, including high-ranking counterterrorism officers, perished in the attack some 135 kilometers (84 miles) southwest of the capital, Cairo.

Prosecutors said Thursday a "foreign" militant involved in that attack was captured alive following a retaliatory airstrike and is a Libyan citizen from the city of Derna, considered a hotbed for Islamic militancy.