Acting chief John Donlan said Tuesday that there was nothing left inside the Blackberry Lane duplex where firefighters found the bodies.
``Everything in this house was reduced to ashes,'' he said. ``There's nothing left. It makes it difficult, when it's that damaged, to find a cause.''
Fire investigators have used accelerant-sniffing dogs to rule out arson, he said.
Killed in the fire were Cherie White, 24, and Ronald Mero, 29; their son, Nathan Mero, 2; Jordan Mero, 9, Ronald Mero's son from another relationship; and Destiny Becotte, 5, White's daughter from another relationship.
Also Tuesday, the duplex owner, Cape Realty Inc., released a statement suggesting that Ronald Mero had disabled the smoke detectors so he could smoke inside the home, in violation of the rental agreement.
Cape Realty released an inspection report signed April 28 by Mero and White, in which they agreed to maintain the smoke detectors and not to smoke inside the building.
In the company statement, Shawn Horan of Cape Realty said a subcontractor who worked with Mero told him that Mero smoked on the job.
``It is our contention that the smoke detectors were disabled by the Tenant and that the Tenant may have been smoking in the unit,'' the statement said.
Neighbors did not report hearing a smoke alarm.
Since the detectors were destroyed, Donlan said fire officials can't know what role, if any, the detectors played in the blaze.
``Whether (the smoke detectors) were maintained, whether they functioned, again those are unanswered questions that will probably never be answered,'' he said.
Donlan said the fire was likely so intense because it burned unnoticed for an extended period. The two-story, wood-frame duplex was engulfed in flames when the first fire crew arrived around 1:30 a.m., officials said.
A middle school and elementary school that two of the fire victims had attended offered counseling Tuesday for their classmates and friends. Meanwhile, neighbors mourned their loss.
``We lost one of the best families on the street,'' neighbor Starr Elliott told the Cape Cod Times. ``They were a wonderful family and they were great kids.''
