(CNN) -- A state prosecutor says he will not file criminal charges in the Stamford, Connecticut, house fire that killed three young girls and their grandparents on Christmas morning last year.
Stamford State's Attorney David I. Cohen said in a statement Friday that after a thorough examination of investigations conducted by Stamford's fire and police departments, including reports, interviews, photographs, seized evidence and autopsy data, there is "insufficient evidence" to bring criminal charges.
The fire, which broke out around 5 a.m. Christmas Day, was probably caused by embers removed from a fireplace, Stamford Chief Fire Marshal Barry Callahan said.
According to Cohen, it remains unclear if smoke detectors were working in the home the night of the blaze, but some precautions were taken.
"While in hindsight, they were obviously insufficient, when viewed from the perspective of that night, they do not rise to the level of criminal negligence," he said.
Lily, 10, and 7-year-old twins Grace and Sarah Badger died in the fire along with their grandparents, Lomer and Pauline Johnson.
The girls' mother, Madonna Badger, and a friend, Michael Borcina, were able to escape.
According to a legal notice submitted to the Stamford city clerk's office, Madonna Badger is suing the city for property damage, personal injury, negligence and civil rights violations.
Two days after the fire, the city of Stamford determined the large Victorian home was unsafe and tore it down.
Badger says the city and some of its employees destroyed her home and its contents, valued in excess of $3 million.
She adds that in destroying the remains of the house, the city destroyed evidence that could have helped bring closure to the tragic incident.
In his statement, Cohen said future fire investigations should be handled differently, suggesting that police and the state attorney's office should be contacted before any demolition of property, and that local fire marshals should contact state fire marshals for an outside perspective.
"When such a horrific event occurs, it is only natural that those related to the victims and the public in general want to hold someone responsible for what is otherwise an inexplicable accident," he said. "I am aware that many have emotionally judged this circumstance differently. That is understandable. There is no way that I could begin to conceive of the depth of loss by the Badger family."