The Los Angeles Police Department has been inundated with tips about where ex-cop Christopher Dorner may be after putting up a $1 million (£638,000) reward for his capture.
The LAPD has so far received around 600 calls regarding whereabouts of Dorner, who published a manifesto saying he would bring "warfare" to its officers and their families.
The 33-year-old is suspected of killing three people, a police officer as well as two civilians - Monica Quan, who is the daughter of a former police chief, and her fiancé.
Dorner believes he was wrongly fired from the LAPD in 2008 for making false statements.
He alleged that his field training officer sergeant Teresa Evens kicked Christopher Gettler, a suspected schizophrenic with severe dementia. The victim's father, Richard, supported Dorner's testimony.
In his lengthy manifesto, Dorner says he is determined to bring corruption within the LAPD to light and that he will not stop his killing spree until the truth is told. He also made assertions about racism within the force.
The LAPD said it was offering a $1 million reward for information leading to Dorner's capture yesterday.
Lieutenant Andrew Neiman said over 600 lines of inquiry are being investigated as of Monday morning.
The police department has been on tactical alert since Sunday, meaning officers are staying on duty beyond their shifts.
Police are guarding people named in the manifesto and their families. There was also a heavier police presence at the Grammy Awards last night due to fears of an attack.
Dorner has amassed huge levels of support since publishing his manifesto online, with many people backing his 'war' on police corruption and supposedly wrongful dismissal.
LAPD police chief Charlie Beck has said he will reopen the disciplinary case that led to Dorner's dismissal after new details emerged about his assertions.
Beck said he promised to hear Dorner out if he surrenders and that he has ordered a review of the case because he takes allegations of racism within the force seriously.
"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," Beck said in a statement.