The murder trial has been set for a man charged in a mass shooting last year at a medical clinic west of the Twin Cities in Buffalo.

Gregory P. Ulrich, 68, is scheduled for trial on May 16 in Wright County District Court on charges of first-degree murder, numerous attempted murder counts and other charges in connection with the Feb. 9 assault at Allina Health Clinic that killed one staff member and injured four.

Conviction by jurors on just the first-degree murder count would mean a mandatory sentence of life in prison without the possibility of parole for Ulrich, who remains jailed in lieu of $5 million bail.

Prosecutors have alleged that Ulrich set off explosive devices — two in the lobby, a third in an adjacent workstation — in about six minutes from the time he entered the building, started shooting and surrendered to officers arriving in the parking lot.

In August, his defense decided not to fight a court ruling that Ulrich was mentally competent to stand trial.

Court records portray the man as a scofflaw with mental health and substance abuse problems who frequently called police to report unfounded thefts or minor quarrels with his neighbors in Buffalo, medical aides, tenants and others.

Also, a former roommate told the Star Tribune that Ulrich was an addict and angry because a doctor refused to give him enough painkillers.

Lindsay Overbay, a 37-year-old medical assistant at the clinic, was fatally shot in the assault. The other wounded staff members were Tammy Schaufler, Sherry Curtis, Antonya Fransen-Pruden and Jennifer Gibson.

County Attorney Brian Lutes said Thursday that Judge Catherine McPherson has blocked out four weeks for the trial, with much of that time expected to be used for jury selection.

"No specific time was set aside for jury selection," Lutes said, "but that process is time-consuming due to the large number of strikes provided in first-degree murder cases and because jurors are typically questioned individually as opposed to part of a panel."

The judge gives lawyers a certain number of strikes to use to dismiss potential jurors without having to explain why.

Also, Lutes said, "jury selection will be complicated by the notoriety of this case."