But at the medical center the problem was work performance. Chen, 42, came to the University of Washington after two years at a residency program at the University of Mississippi. Prior to his arrival, he was a promising scientist, but he began to struggle in one of the nation's most renowned and demanding pathology programs. He became angry and difficult as he was told his work was subpar, and engaged in shouting matches with his supervisors. When his supervisors recommended he consider moving to another program or undergo psychological counseling, he grew more upset.

Some pathology colleagues were so scared by Chen that they started locking their doors when he was around. "There was considerable concern and consternation on the part of the department faculty," says John Coombs, associate vice president for medical affairs and associate dean of the medical school. "And there was fear as well."

That increased when department officials learned that Chen was shopping for a gun. Medical residents saw yellow pages turned to gun shops, and even spotted a map to a gun shop on his computer screen. At a meeting in late May, he was asked by department officials and police if he was going to buy a gun, and he said he wanted one for protection. Officials warned Chen that it was illegal to carry a gun on the UW campus. Because Chen—who had no criminal record—never made a threat against any specific individual, there was nothing more law enforcement or University officials could do. A UW policeman even saw Chen at a Bellevue gun shop but didn't report it until after the shooting.

Two weeks before his final work day, Chen's background check was complete and he was cleared to pick up a .357 Glock semi-automatic pistol, which he had purchased for $479. Chen meticulously planned his suicide—he prepared letters to be sent after his death, including one to Haggitt, whom he apparently did not intend to kill. It is possible that Chen changed his mind and decided to kill Haggitt, or perhaps Haggitt tried to intercede and stop Chen's suicide. The medical examiner's report was inconclusive and we will never know what went on behind those locked doors.

Haggitt, 57, a Seattle resident, was a world renowned gastrointestinal pathologist who helped develop many methods for treating gastrointestinal cancer and disease. A native of Detroit, he spent most of his life in Tennessee, went to medical school at the University of Tennessee, and joined the UW in 1984. Here, the man who loved blues and firing up the barbecue helped establish ways of treating gastroesophageal reflux disease. He also was credited with coming up with the protocol for biopsies in many transplant centers. "It's going to be a terrible blow to us, almost irreplaceable," said Pathology Professor George Martin. Haggitt was survived by his wife and three grown children.

A native of Shanghai, China, Chen had become a naturalized U.S. citizen and had published articles in scientific journals and made presentations at national conferences. He had gotten along well with people at schools he studied at in China, New York, Iowa, Texas and Mississippi. But after he arrived at the UW, he began to struggle. His command of English was less than fluent, and that created problems. So did his stubbornness. Former colleagues say he felt humiliated when his ideas were rejected or deemed too impractical. And when he was told his contract at the UW would not be renewed, he felt even more humiliated. The result was shocking—and deadly.