Thomas Mortimer IV Pleads Not Guilty to Murdering Family

WOBURN, Mass. (CBS/AP) A Massachusetts man accused of killing his wife, two children and mother-in-law in June pleaded not guilty to four counts of first-degree murder in Woburn Superior Court Thursday.

PICTURES: Mortimer Family Murder

Thomas Mortimer IV frowned as he listened to a clerk read an indictment charging him in the murders of his wife, 41-year-old Laura Stone Mortimer, mother-in-law, 64-year-old Ellen Stone and two children 4-year-old Thomas Mortimer V, and 2-year-old Charlotte Mortimer.

The family was found bludgeoned and stabbed to death in their suburban Boston home after a concerned family member could not get in touch with the family and called police.

A prosecutor described how the 43-year-old left two letters at the residence confessing to the gruesome quadruple homicide that stated: "I did these horrible things. What I've done was extremely selfish and cowardly. I murdered my family."

In court Thursday, Assistant District Attorney Adrienne Lynch said officials believe the victims were killed some time between 9:10 p.m. on June 14 and 7:10 a.m. June 15, when Mortimer apparently called his new boss and told him he was not feeling well enough to go into work and also called his son's school to say the boy would be absent.

Authorities found the victim's bodies June 16, a day later Mortimer was arrested in western Massachusetts.

District Attorney Gerard Leone indicated that the slayings followed a fight and "ongoing marital discord" between Mortimer and his late wife. Leone also claimed there were signs that Mortimer tried to commit suicide at the home.

Mortimer had previously entered not guilty pleas in district court and has been held without bail since his arrest. His lawyer, Denise Regan, claims he has mental health issues.

Complete Coverage of Thomas Mortimer IV on Crimesider.