Authorities in Nigeria announced that they have made several arrests following the assassination Sunday of Justice Minister Bola Ige.
Those arrested include at least two members of the Justice Minister's security detail. Nigerian police say a number of other people have been taken into custody and are cooperating with the investigation.
Bola Ige, a close political ally of President Olusegun Obasanjo, was gunned down at his home in the southwestern city of Ibadan late Sunday. Family members say gunmen stormed into his bedroom, opened fire at close range, and fled.
Nigerian police say they do not yet know the motive for the killing.
On Wednesday, authorities posted a reward of more than $4,000 for information that would help solve the shooting.
Mr. Ige's assassination came amid a festering political crisis in southwestern Osun state. The state's governor, Bisi Akande, has been at odds with his deputy governor. Both men belong to Bola Ige's Alliance for Democracy Party. The impasse has resulted in street clashes between supporters of the two men. Last week, a state lawmaker who was an outspoken supporter of the deputy governor was killed.
Political observers say the minister had taken the side of Governor Akande in the dispute.
The assassination prompted President Obasanjo to call an emergency meeting of his cabinet and the heads of Nigeria's armed forces on Monday. The meeting ended with a call for the deployment of troops to Osun state to avert any possible violence in the wake of Mr. Ige's death.
The killing was the first assassination of a major political figure in Nigeria since the country returned to civilian rule in May of 1999.