BIG BEAR LAKE, Calif. -- Clear skies allowed aircraft with heat-sensing technology to aid scores of officers searching in the snow-covered San Bernardino Mountains for Christopher Dorner, the former Los Angeles police officer suspected of killing three people in a vengeance-fueled rampage aimed at those he blames for ending his career.
Two sheriff's choppers flew low over the forest Saturday as SWAT teams fanned out to look for tracks in the fresh foot of powder that fell overnight.
It's the third full day of the massive multiagency effort to hunt Dorner down. He's continued to elude authorities whose last clue of his whereabouts was a burned-out pickup truck found Thursday in this ski resort town.
Investigators continue to analyze the truck to determine whether Dorner torched it or if it caught fire for other reasons.
SWAT teams in camouflage scoured the mountains Friday and went door to door examining vacant cabins, aware to the reality they could be walking into a trap set by the well-trained former Navy reservist who knows their tactics and strategies as well as they do.
"He can be behind every tree," said T. Gregory Hall, a retired tactical supervisor for a special emergency response team for the Pennsylvania State Police. "He can try to draw them into an ambush area where he backtracks."
As authorities weathered heavy snow and freezing temperatures in the mountains, thousands of heavily armed police remained on the lookout throughout California, Nevada, Arizona and northern Mexico for a suspect allegedly bent on revenge and willing to die.
Police said officers still were guarding more than 40 people mentioned as targets in a rant they said Dorner posted on Facebook. He vowed to use "every bit of small arms training, demolition, ordnance and survival training I've been given" to bring "warfare" to the LAPD and its families.
The manhunt had Southern California residents on edge. Unconfirmed sightings were reported near Barstow, about 60 miles north of the mountain search, and in downtown Los Angeles.
Some law enforcement officials said he appeared to be everywhere and nowhere, and speculated that he was trying to spread out their resources.
For the time being, their focus was on the mountains 80 miles east of Los Angeles -- a snowy wilderness, filled with thick forests and jagged peaks, that creates peril as much for Dorner as the officers hunting him.
In his online rant, Dorner baited authorities. "Any threat assessments you generate will be useless," it read. "I have the strength and benefits of being unpredictable, unconventional, and unforgiving."
Authorities in Orange County served a search warrant at a storage unit as part of their investigation into Dorner.
Irvine police Lt. Julia Engen said Saturday that evidence was collected late Friday night from the facility in Buena Park. She wouldn't elaborate on the nature of the evidence or say who had rented the storage unit.