retailers have the best opportunity to spot potential bombers? we want to pay attention to people buying the fertilizer. reporter: right now we have about 250,000 stores nationwide that sell products containing these explosive precursor chemicals, and we need them to report when they see suspicious behaviors around this. reporter: authorities are worried they won t always be so lucky that nobody is killed in a bombing. that was troubling. the california governor has denied parole for the man who killed robert f. kennedy. it s the 16th team that the man has sought parole for the 1968 assassination. a two-person panel found him suitable for parole back in august. the governor explaining his decision in an l.a. times op ed saying in part, he remains a potent symbol of political violence. he maintains he does not