Unclear whether Umaru Musa Yar'Adua will resume duties . The Nigerian government has said it is investigating the attack and that a probe into who was behind it would be conducted by an international team of experts. Lagos , Nigeria ( CNN ) -- His three month absence created a power vacuum in Nigeria .
Unclear whether Umaru Musa Yar'Adua will resume duties . The Nigerian government has said it is investigating the attack and that a probe into who was behind it would be conducted by an international team of experts. His three month absence created a power vacuum in Nigeria .