The manhunt may be over for a former Los Angeles police officer accused of shooting five police officers -- killing two -- and slaying two other people.

Christopher Jordan Dorner, 33, had threatened to target law enforcement officers in retaliation for being fired more than four years ago, authorities say.

Here's a timeline of the case:

2001-2002: Dorner graduates college, joins Navy

Dorner grew up in Southern California before attending Southern Utah University, where he was a running back for the school's football team. He graduated with a degree in political science in 2001.

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He joined the Navy after college, receiving a commission as an ensign in July 2002. He trained in river warfare units and eventually was rated as a rifle marksman and pistol expert, according to Pentagon records.

2005-2006: Dorner starts LAPD career

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Dorner enrolled in the Los Angeles Police Academy in February 2005. After graduation, he spent a few months on the streets as a trainee.

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2006-2007: In Iraq with the Navy

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The Navy recalled Dorner to active duty, and he served a 2006-2007 stint in Iraq guarding oil platforms.

2007-2011: Return to LAPD, termination and appeals

After his tour in Iraq, Dorner returned to the Los Angeles Police Department in 2007. Shortly after his return, he reported excessive force by a fellow police officer in July 2007.

In a letter allegedly written by Dorner and provided to CNN this week, he said he was relieved of his duties in 2008 after he made the report against the other officer. The letter was provided to CNN by an LAPD source after this week's manhunt began.

Dorner tried to get his job back in 2008, but the LAPD's Board of Rights rejected his appeal. He eventually took the case to court, but a judge ruled against his appeal in October 2011.

February 1: Dorner leaves Navy

Dorner was honorably discharged from the U.S. Navy Reserve as a lieutenant, according to Pentagon records.

February 3: Two killed in Irvine

Two people -- Monica Quan, 27, and her fiance, Keith Lawrence -- were killed in Irvine, California, while sitting in a vehicle at a parking structure, authorities said. Quan was the daughter of former LAPD Officer Randal Quan, who, it is claimed in the letter, bungled Dorner's LAPD termination appeal.

February 5: Dorner at Navy hotel in San Diego

Dorner checked into the Navy Gateway Inns and Suites on San Diego's massive naval base, Navy Cmdr. Brad Fagan said. Dorner probably had access to the hotel from having been honorably discharged, which would mean he would have an ID card, Fagan said.

Dorner failed to properly check out of the Navy hotel on February 6, though he was not believed to still be on base, Fagan said.

February 6: Dorner named suspect, police announce threats

Authorities named Dorner a suspect in the Irvine killings. Authorities said he issued a "multipage manifesto" allegedly implicating himself in the slayings and complaining of his treatment in the LAPD.

Police said Dorner made violent threats against Los Angeles police officers. The force assigned officers to protect those connected to the threats.

February 6: Attempted boat theft in San Diego

Investigators said they believe Dorner tried to steal a boat from someone in San Diego. He failed and fled, LAPD Chief Charlie Beck said.

Later, a wallet is found containing Dorner's identification and an LAPD detective's badge near the San Diego airport, police said.

February 7: LAPD officer shot in the suburb of Corona

In Corona, Dorner fired at Los Angeles police officers who were assigned to protect a person connected to Dorner's threats, police said.

One officer was grazed in the head; the wound was not life-threatening, the LAPD said.

The officers returned fire, and Dorner fled.

"Due to damage to the police vehicle because of his gunshots, the officers were unable to pursue him," Beck said.

February 7: Officer killed, another shot in Riverside

Riverside police said two of its officers were shot in an ambush at an intersection. One died, and the other was taken to a hospital.

Authorities believe Dorner drove up to the officers' vehicle at a stoplight and fired with a rifle.

The officer who died, a 34-year-old Michael Crain, had been on the Riverside force for 11 years.

The other officer was seriously wounded but expected to make a full recovery, Riverside Police Chief Sergio Diaz said.

February 7: Police shoot two in Torrance in mistaken identity case

While searching for Dorner, police shot two people in Torrance in a case of mistaken identity, the Los Angeles police chief said.

LAPD officers assigned to protect someone who "was under the most serious levels of threat" saw a vehicle early in the morning that looked like Dorner's, Beck said. He said the vehicle was moving down a street with its lights off.

The officers shot two people in the vehicle, but neither turned out to be connected to the Dorner case, Beck said.

Both were taken to a hospital. One was in stable condition Thursday with two gunshot wounds, and the other was expected to be released shortly, Beck said.

"I ... feel great sadness for the injuries suffered by ... the two uninvolved citizens in Torrance," he said.

Police also shot at another pickup matching the description of Dorner's vehicle in Torrance, but no one was injured in that incident, a senior law enforcement source said.

February 7: Details of manifesto

An LAPD source gave CNN a copy of the manifesto that Dorner allegedly wrote.

In the letter, he allegedly threatened to use his Navy training to harm police officers involved in his case and their families.

"I will bring unconventional and asymmetrical warfare to those in LAPD uniform whether on or off duty," Dorner allegedly wrote.

The letter said he was terminated after he reported excessive force by a fellow officer. The writer said his attacks were retribution for his termination, as well as a culture of racism and violence he said continues within the department.

February 7: Dorner's truck found on fire, police say

Investigators found Dorner's truck abandoned and burning on a forestry road near Big Bear Lake, about 100 miles east of Los Angeles, San Bernardino County Sheriff John McMahon said.

The discovery spurred more officers to converge on the area to beef up patrols and go to every residence in the mountain community. Police searched at least 400 homes in the area.

February 8: Massive search in the mountains

The hunt for Dorner was "extremely dangerous," the San Bernardino County sheriff said, as SWAT teams used snowcats to zoom up a mountain and other officers prowled forest roads in an armored personnel carrier.

"We're going to continue searching until we either discover he left the mountain or we find him," McMahon told reporters at Big Bear Lake.

Elsewhere, U.S. Navy installations throughout California and Nevada were "maintaining a heightened security posture," a U.S. military official told CNN.

February 8: Plenty of weapons

Guns found in the burned truck were also burned, but authorities believe Dorner may have had up to 30 guns with him, said a source with knowledge of the investigation. Dorner was trained in counterinsurgency and intelligence in the Navy, the source said.

In La Palma, California, police searched the home of Dorner's mother, and she and a daughter were cooperating with investigators, Irvine police Lt. Bill Whalen said.

February 8: No sighting of suspect

Authorities temporarily suspended their search until the following day, but expected to complete a search of more than 200 vacant cabins.

Overnight patrols were beefed up with 12 extra two-officer teams.

February 9: The search goes on

Bundled up in winter gear, search teams returned to the pine forests and trails surrounding Big Bear Lake in the San Bernardino Mountains.

Officers trudged through knee-high snow with rifles. Patrols again visited homes in Big Bear Lake, knocking on doors and peeking into windows.

February 9: Police to review Dorner complaint

Los Angeles police announced the department would reopen the investigation into the case that led to Dorner's termination.

"I do this not to appease a murderer," Chief Beck said in a statement. "I do it to reassure the public that their police department is transparent and fair in all the things we do."

Police vowed they would catch Dorner and urged the former officer to turn himself in.

In Big Bear Lake, resident Justin Owen said police asked him whether he had seen suspicious activity. No, he told them.

"I don't think he is up here, to be quite honest with you, in this quite brutal weather," Owen told CNN.

But his father, Ed Owen, said he thought Dorner may have been hiding in any of the houses that serve as second residences in the mountains and are often vacant.

"I would guess the occupancy rate on my block is just 10%," he said.

February 10: A $1 million reward

Los Angeles Mayor Antonio Villaraigosa announced a $1 million reward for information leading to Dorner's arrest and conviction. The reward includes funds from businesses, private donors and community groups.

"This search is not a matter of if, it is a matter of when," Villaraigosa said. "And I want Christopher Dorner to know that."

February 11: Warrant allows for Dorner's arrest 'anywhere'

As the manhunt entered its second week, a "no bail" warrant was issued for Dorner's arrest after the Riverside County district attorney filed a murder charge against the fugitive for the death of Riverside Police Officer Michael Crain.

"That allows him to be apprehended anywhere within California, out of state or out of the country," District Attorney Paul Zellerbach said.

Dorner was also charged with the attempted murder of three other police officers, including a Riverside officer who was wounded when Crain was killed. Authorities also said Dorner opened fire on two LAPD police officers, wounding one, in the suburban city of Corona.

February 12: Shootout kills deputy; body found in burned cabin might be Dorner's

California Fish and Wildlife wardens said they spotted Dorner driving a purple Nissan down icy roads, apparently tailing two school buses for cover.

Wardens chased the suspect, and a gun battle ensued. Gunfire struck a warden's car.

Dorner crashed, ran and quickly carjacked a pickup truck.

The fugitive fled to a nearby cabin and got into another shootout with San Bernadino County deputies, killing one and wounding another, authorities said.

Police tossed smoke devices inside the cabin, which caught fire and burned for hours.

Late Tuesday night, sheriff's investigators said they found charred human remains among the ashes of the torched cabin.

Authorities said it could be days before forensics experts can identify those remains.