APNewsBreak: Computer error affected mine scrutiny

Emergency vehicles leave the entrance to Massey Energy's Upper Big Branch Coal Mine Monday, April 5, 2010 in Montcoal, W.Va. after an explosion at the underground coal mine. ( (AP Photo/Jeff Gentner))

April 13, 2010 1:31:17 PM PDT
A federal mine safety official tells The Associated Press that the coal mine where 29 workers died in an explosion last week should have received a warning letter in October about a potential pattern of safety violations.