BERKELEY— Authorities have confirmed a Berkeley couple found dead, with two cats, in their apartment last month died of carbon monoxide poisoning.

Roger Morash, 35 and and his wife, 32-year-old Valerie Morash, were found dead inside their apartment on the 3000 block of Deakin Street on January 23.

A friend discovered one of the bodies after checking on the couple. Police later discovered the second body along with the two cats, reports said. Investigators initially ruled out carbon monoxide poisoning.

After discovering the bodies, the Berkeley Fire Department sent PG&E crews to test for poisonous gases that are most often released from faulty furnaces, KGO-TV reported.

“All the obvious dangers, including carbon monoxide poisoning, had been ruled out,” said Deputy Fire Chief Dave Brannigan.

During the investigation, authorities collected several items from the Morash’s apartment to test for toxins. The State of California Public Health Department determined no toxins were present, KGO-TV reported.

It was not until necropsy examinations were performed on the couple’s two cats that carbon monoxide poisoning was confirmed as the cause of death. The exact source of the carbon monoxide has not been determined.

Tests to identify the source of the carbon monoxide have been cancelled while police work to address concerns from residents of the apartment building.

Residents say authorities gave the all-clear, but the landlord wanted to test the building again. Further testing was conducted by the Berkeley Police Department on Friday, February 3, KGO-TV reported.