That is the profile of the 102 killers in 100 rampage attacks examined by The New York Times in a computer-assisted study looking back more than 50 years and including the shootings in 1999 at Columbine High School in Littleton, Colo., and one by a World War II veteran on a residential street in Camden, N.J., in 1949. Four hundred twenty-five people were killed and 510 people were injured in the attacks. The database, which primarily focused on cases in the last decade, is believed to be the largest ever compiled on this phenomenon in the United States.

Though the attacks are rare when compared with other American murders, they have provoked an intense national discussion about crime, education and American culture. The Times found, however, that the debate may have largely overlooked a critical issue: At least half of the killers showed signs of serious mental health problems.

The debate was most intense last year, which began with echoes of gunfire in a Salt Lake City television station in January and ended with seven Honolulu office workers dead in November. In between there was a berserk rampage by an Atlanta day trader that left 12 dead and 13 injured. A self-styled fascist attacked a Los Angeles day care center. Seven people died as a hymn ended in a Fort Worth church.

Probably the most shocking were the shootings by two students at Columbine High School who burst into suburban classrooms and killed 13 and wounded 23. The teenage killers were much like the adults The Times studied, but with important distinctions that may bring a better understanding to the problem. [Page 29.] As the anniversary of that crime, April 20, approaches, the questions about crime and culture will inevitably reverberate again.

The Times set out to examine as many of these killings as possible in an effort to learn what factors they and the people who carried them out shared. For while many possible causes have been cited, including violent video games, a decline in moral values and the easy availability of guns, there has been little serious study of this explosive violence.