News World Mark Stevenson, THE ASSOCIATED PRESS Wednesday, May Trio, two thousand seventeen 7:38:Legal EDT PM Postmedia Network file photo Switch text size for the story MEXICO CITY — Mexicans familiar to violent crime are in shock over the cruelty of an onslaught in which assailants raped a woman and her 14-year-old niece, killed her three-year-old son, hammer the spouse,…