TUNIS, Tunisia (AP) — Tunisia's prime minister said Sunday a leading suspect in a deadly museum attack on foreign tourists has been killed in anti-terrorist operations, as tens of thousands of Tunisians marched through the capital to denounce extremist violence. State news agency TAP cites Prime Minister Habib Essid as saying that Khaled Chaieb, also known as Abou Sakhr Lokman, was killed overnight in an operation in the Gafsa region near the Algerian border.