BIG BEAR LAKE, Calif. — With the search for a former Los Angeles police officer wanted in three killings yielding no sign of him Friday morning in a snowy valley high in the San Bernardino Mountains, the authorities were wondering whether he had somehow managed to slip the dragnet.

The police had tried to bottle up the suspect in the resort area around Big Bear Lake, which has only a handful of access roads, and they were confident that they had him trapped. But Thursday pushed into Friday, with no trace of the former officer, Christopher J. Dorner, Mr. Dorner, 33, a former Navy reservist, who has been the target of a huge manhunt since Thursday morning, sought in connection with the shooting deaths of three people and the attempted shootings of several other police officials. A steady snowfall in the region, about 100 miles east of Los Angeles, was slowing the search Friday morning, with more in the forecast.

Sheriff John McMahon of San Bernardino County said the police had spent the night scouring the area around Mr. Dorner’s burned-out car, which had been discovered Thursday afternoon, and trying to follow a set of tracks in the snow that the authorities believe were made by the suspect. Officers went door to door overnight, taking special care to investigate remote cabins and other vacation homes whose owners were away, but they found nothing in any of them.

“We searched all night; we did not discover any additional evidence,” Sheriff McMahon said at a news briefing on Friday morning. “We will continue searching until either we discover that he left the mountain, or we find him.”