92% are male and whites represent 70% of all workplace avengers. >> the massacre that left 15 postal workers dead, 6 wounded. >> the government was a former employee of the standard viewer company and he went about his killings methodically. >> three insurance company executives were killed wednesday when a disgruntled former employee ran into a building cafeteria and began shooting. >> in 1999, 62 people were murdered at work by a co-worker or former co-worker. >> workplace killers, unlike those mass killers who go on a rampage in a public place and target absolute strangers, are very selective and very discerning as to their victims. in fact, there are some killers in workplaces who have literally stepped over some of the people they simply did not wish to kill. >> eyewitness nell jones says barton walked into the offices