The body of a child found in the Southern Calif. home of murder and kidnapping suspect James DiMaggio was positively identified as 8-year-old Ethan Anderson, who was previously thought to have been abducted, the San Diego County Sheriff's department said.
The boy's body was found after fire officials were called to put out a blaze at DiMaggio's home in Boulevard, Calif. and its detached garage at around 8 p.m. Sunday evening.
Inside one of the burned buildings, they found the body of the boy's mother, Christina Anderson, 44, police said.
Investigators also found the badly burned body of a child while searching the scorched buildings, according to the sheriff's department, but did not confirm the body was Ethan until Friday night.
Authorities were able to identify the body after performing DNA analysis extracted through his bone marrow.
DiMaggio is suspected of killing Christina Anderson and her son, Ethan and then abducting her daughter, Hannah, 16, after setting his house on fire.
READ MORE: Amber Alert For Missing Teen Expands After Possible Sighting
DiMaggio and Christina Anderson "were in a close platonic relationship," according to the sheriff's department, and officials said DiMaggio might have had an "unusual infatuation" with her teenage daughter.
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Watch Video An Amber Alert was in effect for both children on Friday until the second body recovered from the home where Christina Anderson was found was identified as belonging to Ethan.
An Amber Alert remains active for Hannah Anderson.
Overnight, hundreds of federal agents and police descended upon a remote, mountainous area of the Frank Church River of No Return Wilderness in central Idaho to further their search for DiMaggio and Hannah, who is believed to be in grave danger, the Ada County Sheriff's Office said.
READ: Amber Alert Suspect's Car Found in Idaho After Possible Sighting "It is treacherous terrain. It is back country. It is wilderness," Ada County Sheriff's spokeswoman Andrea Deardon told ABC News.
Authorities were tipped off to the remote area, located about 70 miles from Boise, after a horseback rider Wednesday reported seeing a man and a teenager matching the description of DiMaggio and Hannah.
"They did appear to have gear with them, they had camping equipment," Deardon said. "I think [the horseback rider] described the interaction as odd, but nothing alarming."
DiMaggio's car was found covered in brush near Cascade, Idaho, on Friday, San Diego County Sheriff Bill Gore said.
The blue Nissan Versa was found without license plates, but authorities were able to determine that the vehicle belonged to DiMaggio through its identification number, Gore said.
While police believed DiMaggio might be armed with explosives and could potentially use them to rig his vehicle or hideout, the Boise Police bomb squad did not find any explosive devices inside or near the car during their initial search Friday afternoon, Ada County Sheriff's spokeswoman Patrick Orr said.
A crew from the San Diego County Sheriff's Department is on its way to Idaho to process DiMaggio's car for evidence.
In the Andersons' hometown of Lakeside, Calif., the siblings' father spoke at a candlelight vigil Friday night after news of Hannah broke.
"We hope that everything is going well to bring her home," Brett Anderson said.
