Oregon State Police fielded about 60 tips after authorities issued an Amber Alert for DiMaggio, 40, and his blue Nissan Versa with California license plate. An additional eight FBI agents were assigned to a command post at San Diego sheriff's headquarters, as state and local law enforcement agencies went opn alert.
"This is a pretty much an all-hands-on-deck effort. It's huge," Fraser said.
On Sunday night, authorities found the body of 44-year-old Christina Anderson when they extinguished flames at DiMaggio's rural home. A child's body was found as they sifted through rubble in Boulevard, a tiny town 65 miles east of San Diego on the U.S.-Mexico border.
The body may be that of 8-year-old Ethan Anderson but Fraser said it could take several days to identify the badly burned remains. Investigators were unable to extract DNA.
DiMaggio, a telecommunications technician at The Scripps Research Institute, was like an uncle to 16-year-old Hannah Anderson and Ethan, and close to their parents for years.
Investigators believe DiMaggio may have had an "unusual infatuation" with Hannah, Fraser said.
"That is kind of a working theory, that it may be something of a motivator," he said. "It's definitely something that we're looking at."
Dawn MacNabb, whose son Alan was close friends with Hannah, said she told her son last Friday that the Andersons were going to visit DiMaggio at his house before he moved.
"She told him Jim was depressed, that it was his last weekend," MacNabb said.
Christina Anderson's father, Christopher Saincome, said his daughter visited DiMaggio's home to say goodbye before he moved to Texas
DiMaggio is wanted on suspicion of murder and arson in the search that began in California and spread to Oregon, Washington, Nevada, British Columbia and Mexico's Baja California state.
Oregon state police said a possible sighting was reported in northeast California near Alturas on Wednesday afternoon, followed by another about 50 miles along the same highway near Lakeview, in south-central Oregon.
Fraser, whose office had several hundred leads on DiMaggio's whereabouts, said the Oregon tip appeared "very credible"
"We're taking it very seriously," he said.