BATH, Maine — Residents of a Brewer building owned by EWT LLC of Concord, N.H. — the owner of the Hyde Park duplex that exploded Tuesday morning, killing 64-year-old Dale Ann Fussell — were hospitalized in 2008 with carbon monoxide poisoning after a technician with an expired license installed a new heating system.

On Friday, Chris Largay, the Bangor attorney who represented several of those people in a lawsuit against Keystone Management Co. and EWT, said he read about the Bath explosion with great concern.

“What concerned me is that if Keystone was managing that duplex in Bath, and Keystone was managing the [apartment] building up here … both had very significant experiences, one that resulted in potential death and one that actually resulted in death.”

The carbon monoxide poisoning in the Brewer building was apparently caused by a separated furnace vent pipe.

A leak in a propane line caused the Bath explosion, the state fire marshal’s office determined Wednesday.

On Thursday, attorney Terry Garmey of Portland sent certified letters placing EWT, Keystone Management and Irving Oil on notice of a potential lawsuit.

Garmey told the Bangor Daily News on Friday that such a notification sometimes leads to a lawsuit, but may also be “a path to exchanging information and resolving a case.”

Garmey said that after talking to “many people” including residents, witnesses and family members, Fussell complained about her heater to Keystone and they had an employee service the units.

“We need to look underneath,” Garmey said. “Somehow, the family needs to understand how the explosion came about, in part so we can rest assured it’s not likely to occur again. We’re going to go as far as we have to go until these important questions are answered.”

The woman who answered the phone at Keystone’s Concord, N.H., headquarters, said Friday afternoon that the company had no comment.