Updated--Simi Valley police say a man killed his mother, the family dog, and then himself in a murder-suicide Thursday night that turned into major law enforcement response because of a threat there might be a bomb in the residence.
Shortly before 7 PM, officers were called to a house in the 500 block of Fairfield Road in the Wood Ranch section of Simi Valley after the discovery of a woman's body in the kitchen.
They found 58-year-old Esperanza Guadalupe Cullen of Las Vegas shot to death.
Police were also told that on a closed upstairs bedroom door there was a message that said "bomb inside don't open explosion."
Police and emergency medical personnel immediately backed out of the house.
The SWAT Team, Crisis Negotiator, Sheriff's Bomb Squad, and a K-9 responded to the scene.
The neighborhood was evacuated and streets were shut down.
Police determined that the house belonged to a married couple with their 33-year-old nephew Michael John Cullen, the son of the woman found shot to death in the kitchen, living there.
It was his bedroom door that had the message about an explosive device.
Hours later, the Bomb Squad's robot entered the building along with the SWAT Team and after searching for an explosive device and not finding any they entered that upstairs bedroom and found Michael John Cullen shot to death.
They determined that he killed his mother in the kitchen downstairs when no one else was home and then killed the family dog and then himself in his upstairs bedroom.
When his uncle came home and found Cullen's mother in the kitchen, he was the one who called the authorities to the scene.
Police say they don't know why Cullen committed the murder-suicide, but they consider the case closed with Cullen the only suspect.