"The bad guy is out there, he has a certain time on you, and a distance. How do you close that?" asked T. Gregory Hall, a retired tactical supervisor for a special emergency response team for the Pennsylvania State Police.
"The bottom line is, when he decides that he is going to make a stand, the operators are in great jeopardy," Hall said.
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.
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, ordinance and survival training I've been given" to bring "warfare" to the LAPD and its families.
At noon, police and U.S. marshals accompanied by computer forensics specialists served a search warrant on his mother's house in the Orange County city of La Palma. Dorner's mother and sister were there at the time, and a police spokesman said they were cooperating.
The manhunt had Southern California residents on edge. Unconfirmed sightings were reported near Barstow, about 60 miles north of the mountain search, at Point Loma base near San Diego, and in downtown Los Angeles.
Some law enforcement officials speculated that he appeared to be everywhere and nowhere, and 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 deep canyons, thick forests, and jagged peaks, that creates peril as much for Dorner as the officers hunting him. Bad weather grounded helicopters with heat-sensing technology.
After the discovery of his truck Thursday afternoon, SWAT teams in camouflage started scouring the mountains.
On Sunday, police say, Dorner shot and killed a couple in a parking garage at their condominium in Irvine. The woman was the daughter of a retired police captain who had represented Dorner in the disciplinary proceedings that led to his firing.