A woman killed her nine-year-old son late on Wednesday by cutting his throat in their home in the province of Trieste town of Muggia (Trieste), sources said on Thursday.     The boy's father, who is separated from the mother and does not live in Friuli Venezia Giulia, called the police as he was unable to get in touch with the woman, a Ukrainian national, the sources said.     The local social services were reportedly following the family's case.     ALL RIGHTS RESERVED © Copyright ANSA