SEATTLE -- It made no sense when Aaron Kyle Huff, a pizza deliveryman, strolled into an early-morning party after a rave in Seattle three months ago and shot eight people at random, killing six before he turned his pistol-grip shotgun on himself.
From his hometown of Whitefish, Mont., where Huff had not made a huge impression despite his bearlike frame, to Seattle, where he lived with his identical twin, the question of "why" turned up blank stares and disbelief.
But instead of closing the book, Seattle Police Chief R. Gil Kerlikowske took the rare step days after the killings of hiring James Alan Fox, a professor of criminal justice at Northeastern University in Boston.
Fox, 54, is among the nation's best-known criminologists, sometimes called the "Dean of Death." The author of 16 books, he was an adviser to President Bill Clinton and has been a frequent guest on the Oprah Winfrey Show.
In about a week, Fox will present his findings to the police. He is confident, he said, that there are explanations for why Huff, who was 28, armed himself with a 12-gauge shotgun, a handgun and nearly 300 rounds of ammunition, and proceeded to commit the worst mass killing here in 20 years.
On the night of March 24, Huff attended a rave - a loose-knit party - at an arts center in Seattle. In the early morning, Huff went by invitation from someone he had met at the rave to a party at a house in the Capitol Hill neighborhood.
Nobody knew Huff, the police said, nor did he leave an impression of rage or resentment.
Near dawn, Huff went to his pickup truck. He retrieved his weapons and ammunition, spray-painted "NOW" on the sidewalk and began his killing spree.
When an officer arrived, Huff put the shotgun in his mouth and killed himself.
Not long after Fox was hired, a crumpled, single-page note was found in a trash bin near the apartment in which Huff and his brother had lived.
Crime lab officials have concluded that it is "highly probable" that Huff wrote the note, which was handwritten and addressed to his brother.
In it, Huff said goodbye to his brother and explained that he was duty-bound to go after the ravers.
"I hate leaving you by yourself, but this is something I feel I have to do," he wrote. "I can't let them get away with what they're doing."