A woman found dead at a boarding house in Waltham early Saturday has been identified as Christin Tobin, 36, the Middlesex District Attorney’s office announced.
The state medical examiner’s office ruled Tobin, who lived in Waltham, died as a result of sharp force trauma, according to a statement jointly issued Sunday night by Middlesex District Attorney Marian Ryan and Waltham Police Chief Keith MacPherson.
Derrick Lopez, 18, of Waltham, is charged with murder, assault and battery causing serious bodily injury, and armed assault with intent to murder in Tobin’s death, according to the statement.
Lopez is set to be arraigned Monday in Waltham District Court.
A family friend who answered the phone at the home of Tobin’s mother on Sunday night said the woman was “still in a state of shock.”
“I’m just a friend of the family, and all I know is that she was loved,” said the friend, a woman who declined to give her name. “She’s going to be missed by her family and friends. ... It’s just a tragedy.”
Tobin was found at 20-22 Adams St. about 2:40 a.m. Saturday by Waltham police who answered a call reporting an assault on a woman, authorities said.
The property is listed in Waltham assessing records as an 18-unit boarding house owned by Martin-Reilly Realty of Bacon Street in Waltham.
The state’s corporate database lists James C. Martorilli of Waltham as the sole officer of the organization. He could not be reached for comment Sunday.Globe correspondent John Hilliard contributed to this report. Jeremy C. Fox can be reached at email@example.com. Follow him on Twitter @jeremycfox.