BRIAN ROSS INVESTIGATES THE DEADLY WORKPLACE SHOOTING SPREE THAT SOME INSIST WAS THE WORST HATE CRIME IN DECADES, ON ABC NEWS' "PRIMETIME LIVE," THURSDAY, MAY 12

Also: George Lopez Discusses the Remarkable, Life-Saving Gift from His Wife

And: A Ten-Year-Old Girl Becomes an Unlikely Hero When Her Mother is Brutally Attacked

Two years after six employees were murdered by a co-worker at Lockheed Martin's Meridian, MS, plant, ABC News Chief Investigative Correspondent Brian Ross uncovers information that the company tried to keep from public view - including reports to company officials more than a year-and-a-half before the shooting rampage detailing death threats made by shooter Doug Williams against black workers. The ABC News investigation looks at internal company documents and the accounts of numerous black and white workers at the aircraft plant that tell a story of open racism and violent threats by Williams. Some of the victims' families say that Williams created a hostile workplace environment that led to what was arguably the worst hate crime against African Americans in decades. "Primetime Live" airs THURSDAY, MAY 12 (10:00-11:00 p.m., ET) on ABC.

Aaron Hobson, one of several Lockheed workers who told management about Williams' threats in 2001, recalls to Ross that Williams "said 'one of these days I'm going to come in here and kill me a bunch of n-ggers, and then I'm going to kill myself.'" Ross reports that the husband of one employee who died in the attack said she had been so frightened by Williams' earlier threats that she increased her life insurance policy. The attorney for another victim's family says, "I can't imagine a hate crime that had more forewarning than this one did." Lockheed and the Lauderdale County sheriff who investigated the case maintain that the shootings, while tragic, were a senseless act of workplace violence. Lockheed, one of America's largest defense contractors, tells "Primetime" that it has a zero tolerance policy for discrimination and harassment, and that the killings were not due to racial discrimination in the workplace.

Also: Every week he makes millions laugh on television, but for years actor/comedian George Lopez was keeping a very serious secret from the world. His health problems recently came to a head and Lopez was faced with a life-or-death crisis when his kidneys began to fail. His wife, Ann, came to the rescue by becoming his organ donor. In his first interview since his surgery, Lopez talks with John QuiC1ones about how this experience has changed his perspective on life in a profound way.

And: With her mother lying on the floor bleeding to death, beaten and stabbed by an angry ex-boyfriend, ten-year-old Katlyn Nelson picked up the phone and calmly called 9-1-1. Her grace under pressure, reports Cynthia McFadden, has made the brave Baltimore girl something of a local hero. Prosecutors say this brutal crime would have ended in tragedy had it not been for the remarkable actions of this very young hero.

DIANE SAWYER, CHRIS CUOMO, CYNTHIA McFADDEN and JOHN QUICONES are the anchors of "Primetime Live." DAVID SLOAN is the executive producer.