On November 1, Mayor Greg Nickels walked into the briefing room at Seattle police headquarters downtown wearing a dark suit and grim face. The previous evening, veteran officer Timothy Brenton, 39, had been murdered in a brazen ambush in the Leschi neighborhood—the first officer killed in such an attack since 1994. Behind Nickels stood four of the city's top-ranking officers, all wearing black bands over their badges.

"We ask you to do a difficult and dangerous job, and you do it every day with excellence," Nickels said, addressing both the officers behind him and the entire Seattle police force. "Please know that you are not alone in this difficult time."

The mayor called the incident "a cold-blooded, premeditated shooting" and promised: "We will not rest until the assailant is brought to justice."

Brenton had a wife and two children, ages 8 and 11, and came from a family filled with people devoted to public safety. His father is a retired Seattle police officer. So is his uncle. His brother-in-law works for the Seattle Fire Department. Brenton himself had worked for the Seattle Police Department for nine years, most recently as a field-training officer in charge of showing the ropes to new recruits—one of whom was in the car with him during the ambush and survived only because she was able to duck below the fusillade of bullets.

The entire police department is now involved in the murder investigation, and while no suspects have yet been named, detectives are "looking at any and every possibility," said police spokesman Jeff Kappel on November 3. Though Kappel wouldn't divulge further details, looking at any and every possibility presumably involves reexamining an incident that occurred on October 22, when three patrol cars and a mobile precinct were burned in a suspected arson at a police department maintenance yard not far from where the shooting of Brenton occurred. No suspect has been named in that incident, either.

What police currently know about the murder is this: On October 31, shortly after completing a 9:30 p.m. traffic stop, Brenton and a police department trainee, Britt Sweeney, had parked their patrol car on 29th Avenue near East Yesler Way. They were discussing how the stop had gone. "Debriefing," said Assistant Chief Jim Pugel, as he recounted the events at the press conference with the mayor on November 1.

The patrol car was facing south. A small car—whitish or light blue or silvery in color—approached from behind. As this car pulled up alongside the officers' patrol car, Sweeney sensed danger. She shouted. She ducked. An unknown number of shots, fired from an unknown weapon, slammed into the patrol car, killing Brenton instantly. One of the bullets grazed the back of Sweeney's neck; she was wearing a protective vest beneath her uniform.

Sweeney called for backup. All available officers in the city responded. She got out of the patrol car and fired back. She'd been on the job as a trainee for a total of six months. Pugel said she showed the coolness and good instincts of a 10-year veteran.

The vehicle the shots came from, containing an unknown number of people, backed up, drove away, and disappeared. The maneuver, which allowed the shooter's car to avoid passing in front of the patrol car's onboard camera and also allowed the shooter to avoid using the relatively busy Yesler Way as a getaway route, suggests a considerable amount of forethought and determination to elude authorities.

"It's a miracle she's alive," Pugel said of Sweeney. "This was an assassination, and every resource is being used to bring it to a conclusion."

Police are looking at the patrol car's onboard camera to see if the suspected vehicle stalked it earlier in the evening. They're also talking to witnesses, following tips, and stopping vehicles that match the description given by Sweeney. "We have people who may have seen it," Pugel said. "We're still trying to determine exactly if they did and who saw it immediately after." On November 3, for instance, the appearance of an old Chevrolet Monza on Capitol Hill—small, light gray, beat-up—drew a huge police response. Officers ordered the occupant out with guns drawn and examined the car's grill (presumably for bullet holes), but then quickly cleared the scene. "Probably nothing," Kappel said afterward, though he added that a lot of cars matching that description are likely to be stopped as the investigation continues.

Police also have arrested a man who was released from jail on October 31 and may have made remarks about intended violence toward police officers. However, Pugel downplayed the significance of the arrest. Pugel asked the public for more tips and any photos taken on Halloween night in Leschi that might have the suspected vehicle—or anything unusual—in the background.

People with potentially helpful information should call the Seattle police tip line (233-5000) or Crime Stoppers, which is offering a $20,000 reward for information leading to an arrest and conviction in this case (800-222-8477, or text to 274637 with "Tip486" in the body of the text). The Seattle Police Officers' Guild is offering an additional $40,000 reward, bringing the total to $60,000.

There had been no recent threats made against Brenton, according to Pugel. "Other than him being a police officer," he said, "there's nothing to indicate they were looking for him."

A public memorial service for Brenton is scheduled for Friday, November 6, at Key­Arena at 1:00 p.m., and a fund to help his family has been set up. Donations can be made at any Bank of America branch to the Brenton Family Assistance Fund.