An Ontario Provincial Police cruiser sits outside the house of Col. Russell Williams in Ottawa February 9, 2010. Canadian police said on Tuesday they are looking at reopening cold cases of slain women after having laid murder charges against the commanding officer of the country's largest military air base. Williams was charged on Sunday with the murder of two women, one of them a soldier at his air force base in Trenton, Ontario. Williams, who is 46 years old and married, is also charged with the sexual assault of two other women after having broken into their homes.