Killings in Russia heighten Sochi safety concerns

Thursday, January 9, 2014 | 6:57 p.m. CST; updated 7:29 p.m. CST, Thursday, January 9, 2014

MOSCOW — Six men are dead in a series of unexplained killings involving booby-trapped bombs in southern Russia, further heightening security fears ahead of next month's Winter Olympics in Sochi.