Dragged across concrete, pepper sprayed and arrested.

That's what an Air Force Officer says happened to him and his wife outside their downtown apartment during protests last month. But he says he wasn’t there to protest – just simply looking around.

“I would never have believed it was possible before it happened to me,” said Alex Nelson.

Nelson said he is a first lieutenant in the Air Force and works in cyber security at Scott Air Force Base. He and his wife, Iris, live near Washington Avenue downtown. During the first weekend of protests, demonstrators made their way to his neighborhood on a Sunday night.

“We had just finished making dinner and sat down to watch tv and we kind of heard some commotion,” he remembers.

The couple went to the rooftop to watch the police response. After a while, he says police dispersed and couple decided they felt safe enough to leave their building and look around.

Nelson said he and his wife did not participate in the protests. After about an hour, they began to walk back home.

“We were about 50 - 60 feet from our front door when all of a sudden a line of police officers started marching in front of us,” he said. “At that point we realized something had gone terribly wrong.”

Nelson describes a police line marching, beating batons on the ground. The couple said they followed police orders to walk in a specific direction, but later became stuck with a small crowd of people surrounded by police.

Nelson said he realized they could be arrested, so he instructed his wife to get down to the ground and put her hands behind her.

“We wanted to not give police any reason to believe we were resisting,” he said.

After that, Nelson said he was pepper sprayed by police, grabbed buy the back of his head by an officer, restrained, and dragged several feet across the street. At one point, he said he tried to explain himself to an officer.

“I told him, sir, I’m an officer in the military. I was out walking with my wife I was not involved in the protests. Can you check my identification, to corroborate my story,” Nelson said. “And he said, ‘I don’t care.’”

Nelson and his wife were taken to the justice center where he said they were released the next evening. He was charged with “failure to disperse.”

Nelson, along with several others, plan to testify Wednesday during a hearing. The ALCU filed a lawsuit against the city of St. Louis, alleging police have acted unlawfully and unconstitutionally toward protestors.

Related: ACLU of Missouri suing St. Louis for unconstitutional police conduct

Nelson is not a plaintiff in the suit, but serving as a witness to offer testimony.

A spokesperson for the city of St. Louis and a spokesperson for St. Louis police declined to comment on pending litigation, Tuesday.

Nelson says he has been trained, during his time in the military, on how to arrest an individual, and that it gives him more perspective on how law enforcement responds to certain situations.

“At the time, I was not resisting and not putting up a fight because I knew, hey – they are doing their job,” he said. But Nelson is still troubled by his experience.

“This could happen to anyone. The sort of the narrative I’ve been told my entire life is, if you’re doing nothing wrong, you have nothing to fear. Something that came to me that night, and nights since is – that’s just not true.”

He added, “I believe that police accountability is incredibly important. And when police aren’t wearing body cameras, and they remove their ID, how can you hold individuals accountable?”

The couple hired an attorney to fight their own criminal charges.