A Muslim sect suspected of a series of targeted killings and a massive prison break has issued new threats in northern Nigeria, this time invoking al-Qaida’s north Africa branch. Posters by the Boko Haram sect appeared at key intersections in the city of Maiduguri this week, bearing the name of Imam Abubakar Shekau, the group’s de facto leader. The two top corners of the posters bore a symbol of an opened Quran, flanked on each side by Kalashnikov assault rifles and a flag in the middle — mirroring of the logo of al-Qaida in the Islamic Maghreb.