Authorities believe the man sought for the killings of four police officers is still alive and has been aided by a network of friends and family, a police spokesman said.
Officers believe Maurice Clemmons was shot in the abdomen during the attack on the officers at a Parkland coffee shop, and had speculated he might have died.
But Ed Troyer, a spokesman for the Pierce County Sheriff, said investigators have questioned several people who had provided assistance to Clemmons since the Sunday morning shootings.
"We think his network of people helping him is running out," Mr Troyer said. "He's probably on his own."
Police are also certain Clemmons, 37, was in a Seattle house on Sunday night, but was able to flee before police could contain the area.
Police staked out the house overnight before determining early yesterday that Clemmons wasn't there.
Clemmons has had access to handguns, rifles and shotguns, Mr Troyer said.
"It's unfortunate he's been a step or two ahead of us."
Yesterday morning's realisation that the suspect had not been cornered after all prompted police to fan out across the city, looking for any sign of Clemmons.
Authorities posted a 125,000 US dollar reward for information leading to his arrest over the Sunday morning shooting rampage.
The manhunt came as authorities in two states were criticised for the fact that Clemmons was allowed to walk the streets despite a teenage crime spree in Arkansas that landed him a 108-year prison sentence.
He was released early after then-Governor Mike Huckabee commuted his sentence.
The case could hurt Mr Huckabee's chances should he make another run for the Republican presidential nomination in 2012.
"This guy should have never been on the street," said Brian D. Wurts, president of the police union in Lakewood, where all four murdered officers worked. "Our elected officials need to find out why these people are out."