There were nine children sleeping in a Unity home in the early morning of September 8, 2018 — including four of Melissa Keller’s — but fire investigators said that didn’t stop her from setting the house on fire.

And, if witness statements are to be believed, she planned the whole thing.

Keller, 36, now of Montville, was arrested Tuesday and charged with arson and attempted theft by insurance deception, among other criminal counts. She is being held at Knox County Jail in Rockland, with her bail set at $5,000 cash.

It was not clear why investigators from the State Fire Marshal’s office waited so long between the fire and the arrest. A phone call to Investigator Jeremy Damren on Thursday was not immediately returned. But the fire seemed suspicious from the outset, according to Unity Fire Chief Blaine Parsons.

“I had the fire marshals there before the fire was out,” he said this week.

The house was destroyed, he said, but everyone inside — encompassing three separate households — was able to safely escape.

If Keller is found guilty of arson, she could face a sentence of up to 30 years in prison and a fine of as much as $50,000.

Melissa Keller Credit: Courtesy of Waldo County Jail

Her defense attorney, Kaylee Folster of Bangor, had no comment, saying she had not yet reviewed the police report.

According to the affidavit filed this week by Damren, on the evening of Sept. 7, 2018, Keller and her four young children, including 5-year-old twins, had brought dinner to her husband at his Bangor workplace. She and the kids left to go home to Unity. After the children were asleep, Keller left them by themselves, the investigator wrote. She drove back to Bangor to surprise her husband, but when she arrived at his workplace for a second time, she found he wasn’t alone. He was with another woman.

There was a fight, the investigator wrote, and Keller told her husband that he was going to see “recklessness” in her behavior that night. Then she allegedly went back to Unity.

For her part, Keller denied this, telling the investigator that she and her husband were not having relationship problems and that she didn’t make a second trip to Bangor that night. She said she woke up that night because her son was coughing, and thought the dishwasher caused the fire.

In his investigation, Damren found that the fire wasn’t caused by the dishwasher’s electronics and did not find any “naturally present” ignition sources.

Keller’s husband told the investigator that in the months before the fire, his wife had suggested burning the house down multiple times.

Damren wrote that Keller and her ex-husband had purchased the home together. After their divorce, she stayed, but was about $14,000 behind in her mortgage payments.

Keller’s oldest son, who was 11 at the time, told investigators his mom woke him up because the house was on fire. She told him to get the twins and leave the house, then go to the apartment next door to tell the neighbors to get out.

There were seven people, including five children, in the other apartment at the time of the fire. Another woman who lived in Keller’s basement was not home because she had just delivered a baby and was still at the hospital. She told investigators that less than a week before the fire, she was with Keller when she got insurance documents in the mail. Keller said she could burn the place down, collect insurance and move somewhere else.

“At the time, she thought that Melissa was joking,” Damren wrote in his affidavit.

Another witness, one of the people who lived in the apartment next door, told police he had overheard a telephone conversation between Keller and her husband about two months before the fire. In that conversation, which was held over speakerphone, the couple allegedly discussed burning the house down to “get out of debt,” and that they’d have to do it when the kids were there, so it didn’t look suspicious.