May will mark the 40th anniversary of a tragedy, its memory eroded by time. On May 18, 1978, an Austin, Texas, police officer was murdered, shot 10 times during a routine traffic stop by a University of Texas honors student-turned-drug dealer.

It was my first week in the newspaper business. A callow teenage obituary clerk at the Austin paper, I watched the sleepy newsroom jolted into action. I saw shock on the faces of veteran reporters, some of whom had covered the 1966 tower shootings on that campus.

The murder of a cop was one of the few things that could still rattle them — the same way it rattles me today, decades later. The way it rattles all of us, entire communities, every time it happens.

You may think your taxes are too high; you may not like the way individual police officers conduct business in particular neighborhoods. You may have had some run-ins with law enforcement yourself.

But at the worst moments of our lives — a car wreck, a missing child, the paralyzing terror of having a gun stuck in your face — help is a three-digit phone call away, no matter who you are. The violent loss of a police officer gives legitimate meaning to that “thin blue line” business.

Dallas patrolman Rogelio Santander, shot last Tuesday by a shoplifting suspect, was not the first U.S. police officer murdered this month. He wasn’t even the only one to die last week: Just a few hours before Santander died, a 62-year-old sheriff’s deputy in rural Maine was shot to death by a suspect who stole his police cruiser.

[Slain officer remembered as gentleman and skilled negotiator]

Yes, there are lot of police officers in this country, and theirs is a risky job. Too easy to forget that they assume this risk on our behalf — until it costs a life.

“Few events are more psychologically destabilizing to a police agency than the death of one of their own in the line of duty,” according to a study published in the International Journal of Emergency Mental Health.

That destabilization spreads outward in concentric waves, as with a rock thrown in a pond: Colleagues, families, other law enforcement departments, entire cities. A cop’s death shocks us as few other tragedies in our cynical, forgetful society can.

I can think of no more descriptive term than “destabilization” to characterize the disorienting shock that gripped this region following the sniper attack summer before last that killed five of our officers and injured nine others.

We get used to most things — sometimes with a rueful what-can-you-do acceptance — especially if they don’t affect us too personally: Auto fatalities, poverty, political dischord, terrible diseases. Bad things happen.

But the murder of a police officer — like the murder of a child — still leaves us shaken, destabilized. There’s a reason both of these are capital crimes in the state of Texas.

In the case of children, we’re heartbroken by their innocence. When it’s cops, we’re unsettled because we’re temporarily reminded of their willingness to accept risks that most of us would not.

[Sister of slain deputy relieved manhunt is over, calls loss of her big brother ‘amazingly painful’]

Every day, they deal with people and situations most of us would take a long detour to avoid. They do it because we share an essential notion of fairness and justice reinforced by law, and somebody has to make sure the rules are followed.

If I live to be 100, I will not forget the name of that Austin police officer who died the week I joined the news business.

His name was Ralph Ablanedo. He was 26 years old, with a young wife and two little boys. He was murdered during a traffic stop by a man who mowed him down with an AK-47 assault rifle. The first backup officer on the scene was Ablanedo’s partner and best friend. The gravely injured officer was able to provide a description before he died of the driver of the car carrying the man who shot him.

And I have qualms about the death penalty, but felt no regret when his killer was executed 32 years later, after a record stay on Texas’ death row.

Thousands of other police officers have since died in the line of duty. Colleagues and families and departments and cities have been shaken, rattled, destabilized. Nobody gets used to it.

But time moves on, and we regain our balance, or stability — until another officer loses his or her life.

There’s a short street in South Austin named Ralph Ablanedo Boulevard, but you likely have to be of a certain age to remember why.

That, or you have to be a cop. They remember him — the same way they’ll remember Rogelio Santander.

Jacquielynn Floyd is a Dallas Morning News columnist.

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