Law enforcement officials in Northern California were proceeding cautiously Friday through an area of steep, wooded terrain as they track a man suspected of killing his wife and two young daughters, then fleeing to the remote backcountry where he grew up.



Shasta County sheriff's Lt. Dave Kent said the search team has been expanded as members hike the tree-lined canyons where 45-year-old suspect Shane Franklin Miller is believed to have taken cover.



"Today we're making a push to walk in and try to find him in the heavy brush,'' Kent said. ``He may be going to a cabin. He may be hunkered down in the brush. It's very strategic how we're moving through that forest area.''



Miller is suspected of slaying his family Tuesday night in the rural community of Shingletown, then fleeing 200 miles west in his pickup truck to Humboldt County. His mother told The Associated Press she had no idea whether her son and daughter-in-law had suffered marital problems or why Miller might turn on his family.



"I can't speak to that. I don't know,'' Joan Miller said in a telephone interview. ``It was none of my business. This just breaks my heart.''



Joan Miller said she has not spoken to her son since the manhunt began.



"Heck, no. I honestly don't know a thing. This is craziness,'' she said.



Miller has been described by authorities as armed and extremely dangerous.



Kent said detectives continue to search his home, where the killings occurred, for evidence and clues as to where Miller might have been headed. The pickup truck he abandoned near Petrolia also is being searched.



Miller grew up in coastal Humboldt County, and authorities say his ability to fortify himself in the mountainous area called the ``Lost Coast'' makes searchers vulnerable.



"It would be easy to hide out up there,'' said local resident Phil Franklin, one of hundreds ordered to lock their doors and shelter in place as the manhunt expands.



To imagine the ruggedness of the landscape, think ``Jurassic Park'' because some of the movie was filmed there. Many residents live off the grid on unmarked back roads often shrouded in a coastal fog.



Like Franklin, most Lost Coast residents are armed because law enforcement patrols are rare on the peninsula that juts into the Pacific.



"The county is strapped for money so we don't have police protection out here,'' Franklin said. ``We all contact each other if something occurs so we can coordinate help.''



Miller is familiar to law enforcement. He once tried to make a living growing one of the region's biggest cash crops _ marijuana. In 1996, he was convicted of felony cultivation in a county known worldwide for the high quality pot grown in the same hard-to-reach forests authorities now are combing.



In 2002, Miller was charged in San Francisco with making and selling marijuana for distribution, being a felon in possession of a firearm, possessing a machine gun and money laundering, according to court records. He pleaded guilty to being a felon in possession of a gun and was sentenced to three years and 10 months in prison. He was released in May 2007, according to the federal Bureau of Prisons.



Miller served 46 months in federal prison for being a felon in possession of a firearm, court records show.



He apparently stayed off the radar of law enforcement until 7:45 p.m. Tuesday, when Shasta County sheriff's deputies received a call from his house. When they arrived, they found the bodies of Miller's wife, Sandy, 34, and two daughters, Shelby, 8, and Shasta, 5.



All three had been shot multiple times, Kent said.



Kent said investigators believe the call was placed by one of the victims because the shooting was in progress.



Authorities also have not recovered the gun, or guns, believed to have been used in the shooting, but Kent said more weapons were found in the house.

