Los Angeles police said Saturday that they would reopen an investigation into the firing of Christopher Jordan Dorner, a former cop accused of killing three people as part of a revenge plot targeting law enforcement officers.

Dorner wrote a manifesto declaring war on police in retaliation for being fired from his job as an LAPD officer and losing an appeal to be reinstated. He promised to bring "unconventional and asymmetrical warfare" to officers and their families, calling it the "last resort" to clear his name and strike back at a department that he says mistreated him.

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

He said police would also look into any allegations made in the manifesto.

Beck addressed what he described as the "ghosts of the LAPD's past," and said that one of his biggest worries was that those ghosts would be "resurrected by Dorner's allegations of racism."

"As hard as it has been to change the culture of the Los Angeles Police Department, it has been even more difficult to win and maintain the support of the public. As much as I value our successes in reducing crime, I value even more our gains in public confidence," he said.

The development came as police continued their search for Dorner, 33, in snowbound mountains. Bundled up in winter gear, teams returned to the pine forests and trails surrounding Big Bear Lake in the San Bernardino Mountains.