Police on Thursday arrested a man they allege led an al-Qaida-linked gang that carried out the killings of four French tourists in December. The suspect was identified as Maarouf Ould Hadib. Police found him in a taxi in the capital disguised as a woman, said Mohamed Abdallahi Ould Adda of the Islamic nation's judicial police force. Adda called Hadib a "dangerous member of al-Qaida" and said he organized the Dec. 24 killings of four French visitors. The tourists were gunned down Dec. 24 on the side of a Mauritanian highway, where they had stopped to have a picnic near the town of Aleg, about 250 kilometers (155 miles) south of Nouakchott. Mauritanian officials say the men behind the attack were linked to an al-Qaida-affiliated terror cell headquartered in neighboring Algeria.