If it wasn't for the photograph of the clench-jawed cop straining at the leash of his German shepherd as it lunges into the belly of a black teenager, there would probably be no Civil Rights Act, no Voting Rights Act, nor any sort of equal rights act at all.

There certainly would have been no "Bloody Sunday" march in Selma, which marks its 50th anniversary this month and is currently playing in a movie theater near you.

It was this image of the cop and the dog and the boy — snapped in Birmingham in 1963, two years before Bloody Sunday — that brought the question of American apartheid to a head.

In early 1963, Martin Luther King Jr. and the movement he led were stuck in the mud. They could claim few in victories in Alabama since Rosa Parks had inspired the Montgomery Bus Boycott eight years earlier. They needed something. So King's Southern Christian Leadership Conference sent 3,000 black school kids into the streets to protest segregation and all the shit that went with it.

In response, Birmingham Commissioner of Public Safety Eugene "Bull" Connor unleashed police dogs and fire hoses, and ordered the mass arrest of the children. Associated Press photographer Bill Hudson was there with his camera.

The photograph of the boy being set upon by a snarling dog ran on nearly every front page in America (though not in Birmingham). President John F. Kennedy said it made him sick.

From that point, history unfolded. Birmingham's desegregation. The 16th Street Baptist church bombing by the KKK that killed four school girls in Birmingham. The Civil Rights Act. Selma. The Voting Rights Act. The assassination of King.

For years, the men in the picture — the scene is also immortalized in bronze in a park in the center of Birmingham — remained nearly anonymous. The 15-year-old boy, Walter Gadsden, was reached three decades later by Pulitzer Prize winning historian Diane McWhorter. Their conversation was short. He said he didn't want to "become involved" and politely hung up the phone.

The Birmingham police officer, identified by McWhorter and his former colleagues in the police department as Dick Middleton, told McWhorter that the photograph "didn't bother me."

Black teen, white cop — more than 50 years later, it's still the stuff of headlines. I believed the two men would have more to offer history than two short phone interviews, so I went to find them, hoping they were still alive.

I found no record of Gadsden having died, but he seems to have vanished into history. No phone. No next of kin. I went to his last known address on the east side of Birmingham. I peeled back some broken security bars, slid my hand through a ripped screen, and knocked on the door. An old, thin black man answered. I showed him the photo.

"No, not me," he said, wheezing like a kazoo. "But I was there."

"Has anything changed?" I asked.

"Yes, a lot has changed," he said. "And then again, not a whole lot has changed."

And with that he closed the door.

Dick Middleton would now be 81. Nolen Shivers, an old buddy of Middleton's from the Birmingham Police Department, confirmed that the man in the photograph is, in fact, Dick Middleton. They worked together for 20 years, and they were both on duty the day the photograph was taken. Shivers, who was assigned to the jail that week, says he booked hundreds of people and was probably the man who took King's fingerprints and mug shot.

"I knew Middleton, and I wrote his name down many times in the docket books where he had made an arrest," Shivers told me.

Segregation was wrong, Shivers says now. But he does not apologize for performing his duties.

"In my eye, I done nothing wrong while I was working," he told me. "I was just doing a job."

The statue in Birmingham's Kelly Ingram Park. (Photo via Flickr)

I wondered what Middleton might say. His voter registration lists two addresses. One, a European bakery owned by his wife. The other, a house in suburban Birmingham. If Middleton had been black, that disparity would have no doubt been enough to make him ineligible to vote back in the Jim Crow South, when simply being born out of wedlock was enough to steal a man's right to vote. I called his house numerous times. I called the bakery. I left messages. He never called back.

Then I went to his front door. A dog yipped from inside the house, and a meaty-faced, middle-aged white man eventually opened up. He was Middleton's son-in-law, he said. I asked for Dick.

"He's not here."

I showed the son-in-law the photograph of Middleton holding the dog. "It's not him," the son-in-law said, too quickly and rather unconvincingly.

"He was a Birmingham police officer?" I asked.

"Yeah, but that's not him."

"Who is it?"

"I have no idea."

"Some other Birmingham cop?"

"Yeah."

I was stunned. Dick Middleton has gone down in history as one of the faces of white oppression, and neither he nor his family had anything to say about it. No explanation, no interpretation, not even an "I was just following orders" trope. Just a tepid denial.

I reminded the son-in-law about Dick's phone interview with Diane McWhorter, the historian. I told him about the recollection of Nolen Shivers, Middleton's longtime coworker. This was certainly his father in law in the photograph?

"No. I don't think it's him."

And with that he closed the door.