Muslim police , soldiers accused of killing 133 during riots in 18 days . U.S.-based HRW says main victims were young Nigerian men . Witnesses say police units summarily executed unarmed men and boys . It withheld the names of many of the people it interviewed over the course of 18 days in December 2008 and February 2009 . Human Rights Watch says death toll could be `` substantially higher '' than documented cases suggest .
Muslim police , soldiers accused of killing 133 during riots in 18 days . U.S.-based HRW says main victims were young Nigerian men . Witnesses say police units summarily executed unarmed men and boys . Human Rights Watch says death toll could be `` substantially higher '' than documented cases suggest .