Investigators believe a recent Dresden fire was intentionally set.

No one has been charged in connection with the May 7 fire at 729 Middle Rd. and the investigation continues, Sgt. Ken Grimes of the Maine State Fire Marshal's Office said in a telephone interview May 9.

“The investigation is in its infancy stages...These investigations can take weeks, months, or years,” Grimes said. He would not say what led to the determination the fire was arson.

Arson is a felony in Maine, punishable by up to 30 years in prison, Grimes said.

A neighbor reported the fire shortly before 11 a.m. When firefighters arrived, the fire was mostly out because the heat from it had cracked a water pipe, which then leaked, fire officials have said.

Homeowner Robert Armstrong said May 9 that the determination by the fire marshal's office on the fire's cause was very surprising, because no one was home at the time of the fire. He, his wife and their 15-month-old daughter, the youngest of their five children, had gone to Bath that morning and no one else stayed home, either, Armstrong said.

“I don't see how it was intentionally set. I don't know how they're coming up with that,” he said.

The family of seven is staying at a Bath hotel in two rooms being paid for by their home insurance company, Armstrong said.

The May 7 fire is the latest in a series of challenges the Armstrong family has had. Armstrong said he has had three strokes in the last two years,  and that his 15-month-old has Down syndrome;  last fall's fire required extensive work to repair the home, he said.

“It's difficult,” Armstrong said when asked how the family was doing, two days after the latest fire. “My wife is distraught. We had just got back into the house and my wife had decorated it. We were looking forward to summer, and now we don't know what's going on or where we're going to go,” he said.

In November 2012, the home was also the scene of an accidental fire caused when a space heater ignited something it was close to, Dresden Fire Chief Gerald Lilly said May 8.

The earlier fire started near the same spot in the home as the May 7 fire, Lilly said.