On Friday, as Tammy Lussier prepared to bury Weise, the nephew whom she lived with, and her father, who was among those killed, she found herself looking back over the last year, she said, when Weise began taking Prozac, the antidepressant, after a suicide attempt that Lussier described as a ''cry for help.''

''They kept upping the dose for him, and by the end, he was taking three of the 20 milligram pills a day,'' she said. ''I can't help but think it was too much, that it must have set him off.''

Lee Cook, another relative of Weise, said his medication had increased a few weeks before the deadly shooting on Monday.

''I do wonder,'' Cook said, ''whether on top of everything else he had going on in his life, on top of all the other problems, whether the drugs could have been the final straw.''

The effects of antidepressants on young people remain a topic of fierce debate among scientists and doctors. Last year, a federal panel of drug experts said that antidepressants could cause children and teenagers to become suicidal.

The Food and Drug Administration has since required the manufacturers of antidepressants to warn of that danger on the labels for the medications.

The suicide risk is particularly acute when therapy starts or a dosage is changed, the drug agency has warned. Although some studies link the drugs to an increased suicide risk, the research does not suggest such a connection to violence like Weise's rampage through Red Lake High School.

Without knowing his medical history or precise diagnosis, it is virtually impossible to speculate on what factors may have affected him - the drugs, his underlying depression, a gloomy childhood wrapped in tragedy or something else entirely.

''What I can say is that his physician, I'm sure, made the appropriate recommendations based on whatever the dosages were,'' said Morry Smulevitz, a spokesman for Eli Lilly, which makes Prozac.

The recommended dosage range, Smulevitz said, runs from 20 milligrams to 80 milligrams a day, so Wiese's 60 milligram dose fell in that bracket. Weise, though just 16, was more than 6 feet tall and weighed 250 pounds.

Lussier, who lived with him in her mother's house on the Red Lake Indian Reservation in far northern Minnesota, said she could not understand what else, aside from drugs, had changed to explain the sudden violence.

Since his suicide attempt and 72-hour hospitalization a year ago, Weise had seemed to be improving, she said.

He was receiving mental health counseling and a doctor's care at the medical center on the reservation, she said.