All sorts of reasons can explain a news conference, aside from the obvious one of trying to curtail pesky calls from reporters on a big story.

The strategic purposes run the gamut -- disclosure, confession, endorsement, reassurance and that rarest reason of all, the Siberian tiger of public relations, a plea for help.

For the San Jose police Monday morning at City Hall, it was about seeking the public's help in finding a second man who fired on a cop after a murderous crime spree.

For the politicians who joined them, it was about reassuring the public they understood the risks cops undergo.

You had to go a long way back in San Jose crime history to find a story quite as chilling as Friday night's saga: four armed robberies, a killing, and a shootout with cops.

This was no cat-and-mouse pursuit. According to police, two bad guys stopped at a light, got out of their car, and walked toward a patrolman in his cruiser, firing as they went.

Only the intervention of a second officer who opened fire saved something far worse from unfolding.

To drive home that point, the police Monday released photos showing the trajectory of the bullets through the police car of the first officer, who continued the chase even after the shootout.

One of the bullets struck the officer's pepper spray canister and another the top of his holster. "Had it not been for his canister, he might still be in the hospital, or dead by now," said Assistant Chief Rikki Goede.

Trajectory

"It was a pre-emptive strike," said spokesman Sgt. Jason Dwyer in an email to reporter Mark Gomez. "They are advancing on him. If you look at trajectory of the rounds going into the belt on the outside, they're almost on top of him."

It was the coldbloodedness of the scene that set it apart from any other attempted murder, or even a shootout. In essence, the cop had no place to go: He was trapped.

And that's why it struck such a visceral chord. Nobody who attended Monday's news conference in the council chambers would be surprised to know it had a political angle.

The politicians shrugged away their usual caution about open-meetings law when seven council members, including Mayor Chuck Reed, showed up. So did councilman-elect Johnny Khamis.

On Sunday, the Police Officers' Association had put up a $10,000 reward for help in finding the second suspect. On Monday, Mayor Reed, who has split with the cops on pension reform, matched that figure.

The second man

"Obviously, our police officers are in danger," the mayor said. "So we need to get him (the second man) off the street as soon as possible."

That was an important point for Reed to make. If he is going to reduce the pensions of the cops, he has to show he understands how dangerous their jobs are.

On both sides of the big pension battle, it's too easy to quantify a cop's job as a matter of the market or legal rights. Can we get replacement officers for less? Is the mayor's assault on pensions legal?

What happened Friday night was not a matter of argument. It was real, living proof of the worst that cops face in the field. And it was why all the quibbling about pensions or the ethics of a campaign fell away in the face of the immediate and most important goal -- finding the second guy.

Contact Scott Herhold at 408-275-0917 or sherhold@mercurynews.com. Twitter.com/scottherhold.