Detectives suspect a 32-year-old Santa Rosa man started the deadly fire that trapped and killed his mother in their family’s home, Sonoma County sheriff’s officials said Monday.

Ian Stamp may not have intended to kill his mother, but evidence of a flammable substance in the area of his bedroom indicates he started the 12:30 p.m. Sunday blaze at the Santa Rose Mobile Estates on Brooks Avenue off East Robles Avenue, Sgt. Spencer Crum said.

Stamp and his father escaped the fire, but his mother Elizabeth Stamp, 66, became trapped.

Firefighters found her body near a bathroom in the back of the residence.

Ian Stamp will be booked into the Sonoma County Jail on suspicion of arson and homicide.

A forensic analysis of dental records will be used to officially identify his mother’s body.

When fire broke out in the double-wide mobile home on Bejay Avenue, one of about 120 units in the complex, Stamp’s father woke up his wife to alert her to the fire.

But once he and his son got out of the house, he realized Elizabeth Stamp was still inside, according to sheriff and fire officials.

“The husband told me he and his son exited, thinking his wife was with them. They got outside and found out she wasn’t with them and attempted to go back in and it was too hot,” Rincon Valley fire Battalion Chief Joe Giordani said.

The fire quickly consumed the unit.

The fire response was extensive, in part due to Sunday’s triple-digit temperatures.

While only two engines were used during the firefight, fire officials called 11 engines and support apparatuses to the scene, bringing nearly 40 firefighters to take turns on the effort due to the heat.

As firefighters mopped up the charred remains of the destroyed mobile home Sunday, Ian Stamp stood outside the home, appearing stunned and disheveled.

Crum said it wasn’t yet known precisely what flammable substance Ian Stamp had used or what he was doing.

A deputy guarded the property overnight, and fire investigators waited to start combing through the burned remains until a search warrant gave them permission Monday afternoon.

Giordani estimated damage at $150,000 for the structure and family belongings.

Residences on either side of the burned home had minor damage, he said.

You can reach Staff Writer Julie Johnson at 707-521-5220 or julie.johnson@pressdemocrat.com. On Twitter @jjpressdem. You can reach Staff Writer Randi Rossmann at 707-521-5412 or randi.rossmann@pressdemocrat.com. On Twitter @rossmannreport.