On HLN's "Raising America" on Tuesday, the children's aunt, Andrea Saincome, said that DiMaggio had known the family for years and that it would not have been unusual for the mother and children to be at his house.
"There was nothing out of the ordinary," Saincome told HLN's Christi Paul. "He seemed like a genuinely nice guy. He was close to the kids, and he was friends with my sister and my brother-in-law."
The children were reported missing by their grandparents on Sunday. Giannantonio said he did not know what led them to believe their grandchildren were missing.
Giannantonio would not release any details about how Anderson was killed, but said arson investigators believe they know how the fire was started. Authorities also found burned weapons in the residence.
The sheriff's office released several photos of DiMaggio, and Giannantonio said he was believed to be driving a blue, four-door Nissan Versa with California license plate 6WCU986.
However, he might have switched vehicles, taken public transportation or be hunkered down somewhere, Giannantonio said.
He asked for the public's help, as did Gore.
"We need all the eyes and ears out there we can get in trying to find both DiMaggio and hopefully those two kids," the sheriff said. "Citizens should not try to interfere with this person at all. He's already proven he's a pretty dangerous fella."
Anyone with information about the case is asked to call the San Diego County Sheriff's Department Homicide Detail at 858-974-2321 or submit an anonymous tip to Crime Stoppers at 888-580-8477.