This weekend, I thought a lot about a story I covered 13 years ago out in the central Pennsylvania city of York. In July 1969, in the very week that three humans were soaring beyond earth's orbit to the moon, black and white residents of that red-brick factory town were engaged in a pitched racial war. When the smoke cleared, two people were dead. A white rookie police officer named Henry Schaad had been gunned down as he patrolled a mostly black neighborhood. Later, a black woman from out-of-town named Lillie Belle Allen was gunned down -- shot by multiple bullets from multiple guns, like a scene in a gangster movie -- for the fatal mistake of getting lost in the wrong neighborhood.

For three decades, justice for these two murders was delayed -- which means justice denied. On the 30th anniversary, a local prosecutor wondered why no one had pursued the killers of 1969. Justice in York was also messy. It almost always is. One of the white gang members who was involved in Allen's killing had reformed and become a solid community member with a wife and kids -- but he committed suicide after he was questioned in the probe. Then It came out that the then-current mayor of York -- who'd been a cop in 1969 -- had passed out bullets to young gang members and told them to "kill as many (n-word)s as you can."

But in the end, something remarkable -- and rare -- happened in York at the turn of this century. Justice achieved. The mayor was forced out of politics (although cleared on murder charges). Nine others were convicted for their involvement in the slaying of Allen, including two men sent away on second-degree murder raps. And two men were also convicted for murder for the equally senseless killing of Schaad, the police officer.

It all happened roughly a cannon shot from the fields of Gettysburg, where Abraham Lincoln had said "we hold these truths to be self-evident, that all men are created equal." Those ideals echoed in York, 138 years later. That every human life matters. That violence is almost never justified. That equal justice for all isn't just a slogan. All of those truths should be self-evident. But when they get tossed into the toxic stew of modern politics, they tend to evaporate very quickly.

Yesterday, I was sick to my stomach reading about the beyond-senseless assassination in Brooklyn of two New York City police officers, 40-year-old Rafael Ramos and Wenjian Liu, 32. Liu was the son of a garment worker, a newlywed of just three months; Ramos was a devoted father of two and a model neighbor who'd shovel your sidewalk in a blizzard. They were targeted by a sick and twisted individual on a violent spree -- it began with shooting his girlfriend in Baltimore and ended with his suicide -- not because of who they were as humans, but simply because they wore a police uniform. That's not just tragic, but abhorent, a gut punch to our aspirations for a civil society.

My revulsion isn't anything unusual. Millions of Americans -- from the president and the attorney general to your friends and neighbors on Facebook -- feel the same way. We're sick of the cycle of violence. In recent months, police officers have been targeted in a way that the nation hasn't seen in decades. We've seen two state troopers shot in Northeast Pennsylvania -- one fatally -- and two officers in Las Vegas murdered by a man and woman who wrapped their victims in a Gadsden flag and announced the start of "a revoltuion". In each case, politics provided some of the cover for their grotesque anti-social behavior. But these murders are just one manifestation of a society with too many guns, too loose a handle on the problem of mental illness -- and a deepening chasm of mistrust.

That's why it was painful -- albeit in a duller, all-too-familiar sense -- and extremely unhelpful to see the usual array of bottom feeders, including rejected politicians Rudy Giuliani and George Pataki, convicted felon Bernard Kerik and police union leaders, racing onto to cable TV or Twitter to blame the killing on a host of people who not only weren't the gunman -- but who obviously had not advocated violence of any kind. Like President Obama (???). Or Attorney General Eric Holder. Or most notably New York Mayor Bill de Blasio, whose biggest "crime" apparently was telling his black son to be extra sure to do what the officer says when he's stopped. Some of these unsubstantiated verbal blasts came before the officers' bodies had even left the hospital. How exploitive and sad.

The biggest blame-target became the many Americans protesting the questionable justice in a series of a shootings by police. These include the death of loose-cigarette-seller Eric Garner on New York's Staten Island in a banned chokehold, the shooting of a 12-year-old boy, Tamir Rice, who had an air gun, in Cleveland, and the investigation into an officer's killing of 18-year-old Mike Brown in Ferguson, where the district attorney just make the shocking admission that he allowed a lying witness to testify before the grand jury.

There was no connection, though, between any protest activities and the sick mind that assassinated two officers. Nonetheless, I've actually heard some people say that it's time for the protests to end. That would be a terrible mistake - for two reasons.

For one thing, the leaders and the more-than-vast-majority of the protesters desire the same thing that everyone else who mourns Officer Ramos and Officer Liu wants tonight: A less violent America where police are safe...and so are citizens. We don't all agree on how to get there. To me and many others, it seems clear that a police force that is less militarized and more community oriented, where there's real accountability that disciplines and if necessary weeds out the the handful of bad actors who don't live up to the actions of the decent and hard-working majority, will make neighborhoods safer. But the old ways are deeply entrenched. Those who want real change need to remain non-violent -- and, yes, acts of civil disobedience such as "die-ins" are non-violent -- but be more determined than ever.

The other thing is that we've just gone through an episode when Americans are justifiably outraged that a far-away dictator is resorting to illegal computer hacking and terroristic threats to (maybe) cancel a Hollywood movie -- even though it's a movie that no one was clamoring to see. That's because we don't like being told what we can and can't do. Now, some politicians and police union leaders are telling protesters to go home, and shut up -- also because of the actions of one unstable individual? That's just as un-American. This is a time when all Americans who want a more just, and less violent society, need to speak up more loudly than ever, and fight harder for what they believe in. It's the only way to break the cycle.