A Massachusetts man accused of killing his wife, two children and mother-in-law pleaded not guilty Thursday to four counts of first-degree murder as a prosecutor described how he left two copies of a letter confessing to the slayings.

Thomas Mortimer IV was arraigned in Woburn Superior Court on Thursday following his indictment last week. He had previously entered not guilty pleas in district court and has been held without bail since his arrest following the killings in June.

Mortimer 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. He did not look at his wife's family members, seated in the front row of the courtroom.

The family was found beaten and stabbed to death in their Winchester home.

District Attorney Gerard Leone has said that the slayings followed a fight and "ongoing marital discord." Leone said there were signs that Mortimer attempted suicide at the home.

The revelation that BP's Texas City refinery emitted toxic benzene for more than a month has ignited a furor in the port community that has suffered its share of deadly industrial accidents and toxic spills.

Thousands of residents who fear they may have been exposed to the known carcinogen released at the oil refinery from April 6 to May 16 have been flooding parking lots and conference halls where local trial attorneys hosted information sessions and sought clients for class-action lawsuits against the oil giant.

BP faces the new challenge just as it is reaching a key milestone in another crisis — plugging the Gulf of Mexico well that blew out in an oil spill disaster that is costing the company billions of dollars.

On Wednesday, more than 3,400 people lined the hallways and sidewalks around the Nessler Center to sign on to a $10 billion class-action lawsuit filed Tuesday in Galveston federal court by Friendswood attorney Anthony Buzbee.

The lawsuit alleges the release of 500,000 pounds of chemicals - including 17,000 pounds of benzene - has jeopardized the health and property values of people who live and work in the area. At the nearby College of the Mainland, a separate town hall meeting drew a crowd of 600.

The doctor charged in Michael Jackson's death is due back in court for a scheduling hearing that will determine when prosecutors will publicly present some of their evidence.

Dr. Conrad Murray is required to attend Monday's hearing, during which a Los Angeles judge is expected to schedule a preliminary hearing for later this year.

The judge will decide at that hearing whether there is enough evidence for the involuntary manslaughter case against the cardiologist to continue. Murray, who maintains offices in Las Vegas and Houston, was charged in February for administering a lethal dose of anesthetic propofol to Jackson.

Murray has pleaded not guilty and his attorneys have said the physician did not give Jackson anything that "should have" killed him.