Providence Detectives Bill Baldasore, left, and Joe Donnelly, carry the boiler from the Blackstone Avenue house where three people died.

The Providence Journal / Steve Szydlowski

PROVIDENCE — Police detectives yesterday removed a boiler, boiler vent piping and a hot-water heater from the basement of a South Providence house where carbon monoxide killed a family of three, and held them as evidence.

Faulty installation of the boiler caused the deadly gas to accumulate in the house sometime during a seven- or eight-day period beginning about New Year’s Eve, according to city and state investigators. They have not been specific about what was faulty or when the family was overcome by the fumes.

The police are seeking the identity of the installer, who they have said could not have been a licensed plumber because the installation was so clearly done wrong.

The case bears the hallmarks of a criminal investigation — Assistant Attorney General Scott Erickson inspected the scene at 345 Blackstone St. on Tuesday and conferred with the police — but the police won’t characterize it.

And Dr. Thomas Gilson, the Rhode Island chief state medical examiner, who concluded that carbon-monoxide poisoning was the cause of death and that “no foul play is suspected,” yesterday refused to make public his formal finding regarding the manner of death.

He sent word through a spokeswoman that as a matter of policy, he will not publicly pronounce the case a homicide, suicide or accident.

Criminal laws can come into play even when a death was not the intended result of an action. For example, Daniel M. Biechele, who set off the pyrotechnics that caused the Station nightclub fire in 2003, which killed 100 people, pleaded guilty to 100 counts of involuntary manslaughter and was imprisoned.

“From the very beginning we said we would investigate this case as if it was a homicide,” Deputy Police Chief Paul J. Kennedy said yesterday, “meaning that we would be meticulous about the interviewing, collection of evidence and analysis of evidence.”

“In a nutshell,” he said, “all of the resources at our disposal will be utilized.”

While the medical examiner has not yet confirmed the identities of the victims through dental records, a neighbor and a friend have said that Sonia M. Flores, 46, her son Ryan, 14, a ninth grader at the Met School, and her boyfriend, who was in his 50s, lived in the house. The police consider them the victims.

A pet rabbit that had been kept in the basement also was a casualty of the incident. The police said that a necropsy by a veterinarian determined that the rabbit, too, died of carbon-monoxide poisoning.

Detectives, aided by two workers from the Police Department’s building maintenance unit, used a hand cart to trundle the boiler and then the hot-water heater into a maintenance van. Lengths of silvery boiler vent piping were carried out and placed in a larger van belonging to the Bureau of Criminal Investigation, the police unit that gathers forensic evidence such as fingerprints.

The gas-fired boiler, which apparently was installed as a replacement unit some time around the first of the year, carries the brand name of the manufacturer, Enerjet. Given the dullness of its blue color and an apparent rust spot or two, it is clearly not a new unit.

Mayor David N. Cicilline has scheduled a news conference for this morning at the Public Safety Complex to announce the availability of free carbon-monoxide and smoke detectors and a campaign to educate people about the threat of carbon-monoxide poisoning.

gsmith@projo.com