Jury selection is set to begin today in the double murder trial of 29-year-old Christopher Williams. Williams is charged with killing two and wounding two in Essex in August 2006.
Williams has pleaded not guilty by reason of insanity to two counts each of first-degree murder and attempted first-degree murder.
Prosecutors argue Williams is responsible for his actions.
Police charge that Williams first shot the mother of his ex-girlfriend, then went to an elementary school and killed a teacher while looking for his ex-girlfriend. He allegedly wounded one at the school and another at a nearby apartment.
If convicted, Williams could be sentenced to life in prison.