(CBS/WBZ/AP) EASTON, Mass. - A 17-year-old from southeastern Massachusetts is being held on $500,000 bail for allegedly shooting his mother in the back and burying her body in a shallow grave in her backyard.
Matthew Worster pleaded not guilty at his arraignment in Taunton District Court on Thursday on a charge of armed assault with intent to murder.
Prosecutors say autopsy results will dictate if the charges will be upgraded to murder.
According to CBS affiliate WBZ, Worster's mother, 42-year-old Beth Spartichino, had recently divorced her husband and Worster moved in with his father.
Police received a call Wednesday night reporting Spartichino was missing.
An investigation led to Worster's arrest hours later and the discovery of his mother's body early Thursday.
A state police bomb squad was called in after officers found gunpowder and other dangerous materials at the home.