Luigi Mangione will argue a psychiatric defense at his state murder trial in the killing of UnitedHealthcare CEO Brian Thompson, a judge said Wednesday.

Luigi Mangione’s attorneys will present a psychiatric defense at his state murder trial this fall, arguing he killed UnitedHealthcare’s chief executive while experiencing an extreme emotional disturba...

A jury that accepts such a defense would be obligated to convict Mangione of manslaughter, which carries a maximum sentence of 25 years in prison, instead of murder, which could put him behind bars fo...