BERKELEY (CBS SF) – A couple found dead in their Berkeley home under mysterious circumstances earlier this week was killed by carbon monoxide poisoning, a law enforcement source told KPIX 5 Friday.

35-year-old Roger Morash and 32-year-old Valerie Morash were found dead Monday afternoon in a fourplex on Deakin Street in Berkeley where they had lived for several years.

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The source said that the couple was using a laser 3-D printer that was venting into their residence. Symptoms and signs consistent with carbon monoxide poisoning were found in their bodies.

Police evacuated the apartment building and called in PG&E and the fire department’s hazardous materials team to look for a gas leak or some other hazard but no contaminant was found.

Their two cats were also found dead. The couple was identified by authorities Tuesday.

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Roger was a game developer working on an adventure game called Shard. Valerie was a postdoctoral research fellow at the Smith-Kettlewell Eye Research Institute in San Francisco.

They both attended the Massachusetts Institute of Technology.

A memorial service is planned for 6 p.m. night at the Ed Roberts Campus on Adeline Street in Berkeley.

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