PHOTOS: A tense manhunt amid tragic deaths 
 
 That day four years ago, authorities now allege, was the start of a free fall into despair and deadly violence for Dorner. More than 24 hours after Dorner allegedly shot and killed one police officer and injured two others, police say they have no idea where the former cop with a vendetta against police has gone. PHOTOS: A fugitive's life on Facebook 
 
 Born in New York state, Dorner grew up in Southern California with his mother and at least one sister, according to public records and claims in the manifesto. As a teenager in La Palma, Dorner joined the Police Department's youth program, and decided to pursue a career in law enforcement. Over the next several years, military records indicate Dorner received extensive combat and counter-terrorism training and earned commendations for his marksmanship with rifles and pistols. Months later, the Navy called him back into service and he departed for a 13-month deployment in Bahrain. Around 20 minutes later, Dorner pulled up across from a Riverside police department patrol car at a stop light and fired his rifle at them, killing one officer and injuring another before fleeing.
– The California resort town of Big Bear Lake has had a rough night. Los Angeles police officers have visited more than half the area's homes as they search for ex-cop Christopher Dorner; they're telling locals not to answer their doors unless they're sure who's knocking, ABC News reports. Meanwhile, surveillance aircraft are patrolling the skies and fleets of SUVs are keeping watch on the roads as the town is in lockdown, the Los Angeles Times reports. Police say they found Dorner's pickup truck torched on a forest road, with footprints trailing away through the snow. That snow could help hide Dorner, but could also make any movements on foot difficult, the Times notes. More details about Dorner's past are emerging: While longtime acquaintances recalled a "typical guy" who was "never disgruntled," police had long been concerned about him. Four years ago, when he faced a disciplinary hearing the day he was fired from the department, armed guards were on hand, the Times adds. "It was clear ... that he was wound way too tight," an officer says. Click to read about the bizarre package Dorner reportedly sent Anderson Cooper.