U.S. and Haitian authorities say there is growing evidence that a member of President Jean-Bertrand Aristide’s Cabinet plotted to murder a political enemy.

The charges, and Aristide’s refusal so far to deal with them, underscore the deep fissures that remain in Haiti’s highly polarized society and the difficulty facing the United States and the United Nations in working to build functioning systems of law and justice in a country that has spent most of its nearly 200 years of independence under dictatorship.

The FBI-led investigation into the alleged participation of Interior Minister Mondesir Beaubrun in a plot to kill Mireille Durocher-Bertin - and Aristide’s unwillingness to suspend the minister - have plunged U.S.-Haitian relations to their lowest level since U.S. troops occupied Haiti six months ago to restore Aristide to office.

New details of the investigation, obtained from U.S. and Haitian authorities familiar with the case, suggest Beaubrun not only knew of the plot, but supplied a vehicle to carry it out.

No one is suggesting Aristide knew of or sanctioned the killing. But his unwillingness to take steps against Beaubrun has revived old questions about the president’s willingness to tolerate abuses by his supporters.