Apartment red-tagged where Berkeley couple, 2 cats died

BERKELEY, Calif. (KGO) -- In the East Bay, there's still a lot of mystery surrounding the tragic death of a young couple in Berkeley and their pets last month.

RELATED: No signs of trauma in deaths of 2 people, 2 cats in Berkeley

The apartment where Roger and Val Morash died of carbon monoxide poisoning has been red-tagged, but where the gas came from remains unknown.

Marie Nadeu is always testing her carbon monoxide detector and for good reason.

The apartment three doors down is now red-tagged. It's where the Morahses and their two cats died on Jan. 23 from carbon monoxide poisoning.

THe remaining units have been inspected several times and have been declared ssafe. Nadeu is not convinced.

When asked if she was nervous staying here she responded, "On and off. I try not to turn heater on too much."

Another neighbor said, "What I think is strange, they can't find the source."

A police investigation never found the source of the carbon monoxide poisoning, so the city is now giving the building's owner 15 days to hire a mechanical engineer to find it and report back to city hall.

Some neighbors don't think anyone should be living here in the meantime.

"I wouldn't live there for all the tea in China, would you?" asked Berkeley resident Jim David.

RELATED: Berkeley couple died from carbon monoxide poisoning

The owner has 90 days to repair the source in apartment four before anyone can live there again.