A former nurse at a veterans hospital in Northampton was convicted of murdering four patients with drug injections in what prosecutors said was an attempt to impress her boyfriend with the way she handled emergencies.
Kristen Gilbert, 33, could get the death penalty.
Massachusetts banned capital punishment in 1984. But the case was tried in federal court, where murder can be punishable by death because the crimes took place on federal property, the Veterans Affairs Medical Center.
Gilbert's lawyers blamed the emergencies and deaths on natural causes, saying the patients were already ill.