Officer Tim Brenton is seen in an undated photo provided by Seattle Police.

According to police documents, the man on Friday threatened a King County Jail sergeant who had been assigned to his pending case. The man told the sergeant he might have to "take someone out" and talked of killing a Seattle police officer and corrections officers, investigators said.

The man was arrested at his home on Friday, but made bail on Saturday. Dispatchers told officers that the man had again made threats as he left the jail, documents said.

Even though court documents have identified the man as a person of interest in the case, investigators said they have not narrowed their search to just one person.

"We've talked to scores of people - people who have made threats, either directly or indirectly to law enforcement, not only seattle police officers, but others - and we're pursuing leads there," said Asst. Police Chief Jim Pugel.

After Officer Timothy Brenton was shot and killed Saturday night, police went to look for the man as a person of interest and found him in a car outside his apartment in South Seattle.

Officers say he refused to step out of the vehicle, had to be forcibly removed and was booked for investigation of obstruction. Seattle police would not comment, except to say their investigation into Brenton's death is ongoing and they have not ruled anything out.

Meanwhile, Seattle Police Interim Chief John Diaz said earlier Monday that Brenton's killing appears to be random as the reward for the killer's capture climbed to $40,000.

Detectives believe the killer watched the traffic stop conducted by Officer Timothy Brenton and a student officer before pulling up alongside the patrol car and opening fire, Diaz said in a briefing to the Seattle City Council.

"This was a hit on law enforcement," Diaz said. "This was a hit on government. It could have been anybody."

Brenton, 39, was killed instantly. The officer he was training, 33-year-old Britt Sweeney, was grazed by several bullets and was able to return fire.

"She is lucky to be alive," Diaz said, "and we believe she may have hit the car."

Investigators believe the gunman may have watched the two officers at an earlier traffic stop before opening fire minutes later as they sat in their patrol car.

In the briefing to the council, Diaz said investigators are looking at a massive amount of video gathered from the area.

"We pulled every in-car video camera from all the vehicles that worked in that area, going back several hours. We're also checking all the videos from all the businesses," and red light cameras, he said.

Brenton was a nine-year veteran of the department, but his roots - in the region and in law enforcement - run much deeper. He graduated from West Seattle High School in 1988. His father and his uncle are both retired Seattle police officers.

Brenton joined the Seattle Police Department after working as an officer in La Conner. He was most recently a part of the East Precinct Anti-Crime Team -- a job that made him a hero to the community he served.

The fallen officer is survived by a wife, an 11-year-old daughter and an 8-year-old son.

Flags throughout the city are flying at half-staff in honor of Brenton, and Diaz said a memorial will likely be held late this week or early next week.

"We're looking for a large venue," he said.

A candlelight vigil and service honoring the fallen officer were held at St. James Cathedral on Monday night.

"Any time we lose a police officer it's a tragedy, but this loss is particularly painful because Ofc. Brenton and his partner, Ofc. Britt Sweeney, were ambushed," said Seattle City Council member Tim Burgess.

Diaz said information is already coming in on the department's tip line (206-233-5000), and Clear Channel Communications has donated four billboards that will be used to recruit more tips.

Sweeney is recovering at home as she works with investigators.

As part of a wide-ranging investigation, police are looking for any possible connections between the shooting and the Oct. 22 torching of four police vehicles at a Seattle maintenance yard. Police spokesman Sean Whitcomb says the timing and sophisticated nature of both attacks warrant scrutiny.

Interim Chief John Diaz told a City Council briefing Monday that the slaying was a "hit on law enforcement."

"We're going to do everything in our power to find this person," he said. "Every local and state agency is helping."

In the Central District neighborhood where Brenton was killed, a memorial is growing near the scene at the intersection of 29th and Yesler.

People from the neighborhood, as well as law enforcement officers from around the region are stopping to leave flowers and cards.