An investigation continues into the deaths of two people last week at a home at 555 Belfast Road in Freedom, above, along with two others who were hospitalized, the result of apparent carbon monoxide poisoning. Amy Calder/Morning Sentinel file

FREEDOM — Two people who died at the site of a former illegal marijuana grow house by apparent carbon monoxide poisoning have been identified, authorities confirmed Thursday.

Cansheng Zhao, 31, and Bolin Zhao, 31, both of Brooklyn, New York, died at 555 Belfast Road on Oct. 22 as the result of a carbon monoxide leak. Two other people were hospitalized in the incident.

While these identifications have been made, the cause of those deaths has not yet been determined. On Friday, Lindsey Chasteen, office administrator at the Office of Chief Medical Examiner said via email that further studies are pending.

Freedom firefighters and Waldo County Sheriff’s officials responded to the residence on Belfast Road after receiving a 911 call just after 6 a.m. Oct. 22 reporting several people unconscious inside the home.

The person who called 911 to report the leak told a dispatcher that the people at the Freedom house did not speak English. Asked what language they do speak, the caller told the dispatcher that it was Cantonese or Mandarin. A transcript of the call was obtained by the Morning Sentinel through a public records request.

“He said he can smell the (unintelligible) he thinks the propane’s leaking,” the caller said. “Three are very sick and one is not even moving.”

Authorities raided the home on Belfast Road in May this year, uncovering an illegal marijuana growing operation with nearly 1,900 plants in various stages of cultivation. No one was arrested during the raid.

The operation is believed to have been a part of a network of hundreds of similar sites inside gutted single-family homes across rural Maine. Federal authorities have said the grow sites may be operated by Chinese transnational criminal groups.

It remains unclear what the people were doing at the house. Freedom fire Chief Jim Waterman said they appeared to be living at the residence, and no signs of marijuana growth or cultivation were found at the property.

Waterman said no carbon monoxide detectors were in the house when officials arrived early on Oct. 22. He said the concentration of carbon monoxide was 40 parts per million — which he described as a high concentration.

Waterman said the venting pipe was disconnected at the top of the heating system, and it couldn’t have separated on its own. It “had to have been disconnected somehow,” Waterman said.

The house and about 10 acres of undeveloped property on Evergreen Lane, about 2.5 miles from the house, are owned by Austin Zhen of Brooklyn, New York.

“The investigation remains active and ongoing,” Waldo County Sheriff’s Sgt. Cody Laite said last week. “As a result of that, we’re not releasing any additional details.”