Hundreds of officers scoured the area near Big Bear, conducting door-to-door cabin checks for any sign of Dorner. A scaled-down search for the suspect continued Monday in woods west of Big Bear Lake, where about 30 officers were searching vacation homes and cabins in "an even more remote area," according to the San Bernardino County Sheriff's Department.

Authorities found a burning pickup truck nearby that turned out to be the vehicle allegedly used by Dorner in a Riverside County attack hours earlier that left one police officer dead and two others wounded, according to the court records.

But as part of a surveillance operation of the associate, investigators were watching a property last Thursday in the San Bernardino Mountains owned by one of J.Y's family members, the records show.

The criminal complaint, filed late last week in U.S. District Court in Los Angeles, does not detail the exact relationship between J.Y. and Dorner, a former Navy Reserve lieutenant.

A criminal complaint filed in federal court raises the possibility that Dorner may have been assisted by "a known associate," identified only as "J.Y."

Dorner, 33, a former Los Angeles Police Department officer and Navy Reserve veteran, is wanted in connection with the deaths of an Irvine couple and a Riverside police officer. Multiple law enforcement agencies are involved in the ongoing search, which triggered statewide alerts in California and Nevada and reaches down to Mexico.

Christopher Dorner's burning truck was found near an associate's property in the San Bernardino Mountains last week, court records showed, suggesting that the fugitive former police officer may have received help evading authorities.

The search is set to resume Tuesday with the same number of law enforcement personnel, officials said.

The court records also provide new details as to why federal authorities developed "probable cause" that Dorner may have been trying to flee to Mexico as the law enforcement authorities were widening their dragnet.

TIMELINE: Manhunt for ex-LAPD officer

Dorner allegedly attempted to steal a boat in San Diego and, after subduing the captain, said he was taking the vessel to Mexico, according to an affidavit filed with the criminal complaint in federal court in Los Angeles. Dorner is accused of telling the captain that he could recover his boat in Mexico.

"The attempt failed when the bow line of the boat became caught in the boat's propeller, and the suspect fled," according to the affidavit by U.S. Marshals Service Inspector Craig McClusky.

After authorities interviewed the boat captain early Thursday, they found Dorner's wallet and identification cards "at the San Ysidro Point of Entry" near the U.S.-Mexico border, according to the court records. That same day, a guard at the Point Loma Naval Base told authorities he had spotted a man matching Dorner's description trying sneak onto the base, the records said.

FULL COVERAGE: Sweeping manhunt for ex-cop

Federal authorities told The Times on Monday night that the court papers reflected their thinking at the time, but they stressed that Dorner could be anywhere.

On Monday, hundreds of officers across Southern California were searching for the fugitive across several counties. Investigators said they were sifting through 800 clues, which began pouring in after authorities announced a $1-million reward for information leading to Dorner's capture.

Dorner allegedly threatened "unconventional and asymmetrical warfare" against police in a lengthy manifesto that authorities say he posted on Facebook. The posting named dozens of potential targets, including police officers, that Dorner allegedly threatened to attack, according to authorities.

The records state that the manifesto was discovered by authorities Wednesday, three days after the slaying of the two Irvine victims, one of them the daughter of a retired LAPD captain whom Dorner allegedly blamed in part for his firing from the force in 2009.

The federal documents also provide new details on Dorner's alleged attack against officers in Riverside County early Thursday.

The first shooting was in Corona after an eyewitness reported a person matching Dorner's description at a gas station to an LAPD officer "who was detailed to the area to protect one of the officials whom Dorner had threatened," according to the court records.

"When the officer drove by the gas station, the suspect exited his vehicle and fired an assault rifle at the officer, hitting the officer's vehicle," according to the court records.

The LAPD later said the officer received a grazing wound.

About 30 minutes later, Dorner opened fire on Riverside police officers "who were in the area searching for Dorner," the documents said. On that detail, the account conflicts with a statement provided to the media by Riverside police officials, who said the officers were stopped at a red light and were not looking for Dorner.

ALSO:

Dorner manhunt extends from Mexico to California

Dorner manhunt: conflicting testimony in ex-cop's firing case

Dorner manhunt: Riverside D.A. files murder charges against ex-cop

-- Robert J. Lopez and Andrew Blankstein