What We Know About the 2013 Excessive Force Complaint Against SC Police Officer

— -- Two years before Police Officer Michael Slager was charged with murder this week for shooting an unarmed black man in North Charleston, South Carolina, Slager was the subject of an excessive force complaint by another unarmed black man.

One morning in September 2013, Mario Givens was asleep at his North Charleston home when Slager banged on his door and demanded to be let in, Givens said. Slager didn't identify himself as a police officer, Givens, 33, said at a news conference today.

Givens said he was then told to put his hands up. "I threw my hands up and he still tased me," Givens said.

An attorney for Givens said today they are planning to sue after a review of the complaint "exonerated" Slager.

"If they had even tried to listen to me and investigate him, [Walter Scott] would have been alive because [Slager] wouldn't have been an officer in the field," Givens said.

Slager was charged with murder this week after he shot and killed Scott, 50, on Saturday. Scott was unarmed and video shows Scott running away from Slager when he was shot.

"It's just shocking that they didn't do anything about it and a man ended up dead," Givens said.

Givens said the electric shock from the Taser was painful and caused him to fall and injure his arm. He said he started yelling for his mother after the shock. "Thank God my mom had been there," Givens said, otherwise it would have been "a lot worse."

Givens was then dragged outside, handcuffed and put in a police car, according to an earlier interview he gave to the Associated Press.

The narrative from the police report obtained by ABC News says Givens "refused to exit the residence and tried to close the door because he is afraid of the police."

Givens was initially accused of resisting arrest, he told the AP, but was later released without being charged.

It turns out the police had been looking for Givens' brother, Matthew Givens, after Matthew Givens' ex-girlfriend reported him to the police, according to the AP.

The ex, Maleah Kiara Brown, who was at Givens' home during the incident, told the AP she kept telling officers they had the wrong man, but they didn't listen.

Slager "was cocky," Brown told the AP. "It looked like he wanted to hurt him. There was no need to tase him. ... He was no threat -- and we told him he had the wrong man."

Givens said to reporters today that the woman who took his complaint at the police station "was nonchalant about it."

In a report filed by Slager and another officer involved, Slager said he feared Givens might have a weapon because he couldn't see one of his hands, according to the AP. Slager also claimed he entered the house to keep Givens from fleeing, the AP reported.

According to the police report, Givens' complaint was assigned for review on Sept. 17, 2013, and completed Oct. 4, 2013. The police report classifies the case as "exonerated."

Authorities say they are re-examining past cases and arrests involving Slager in the wake of the shooting death of Scott. Slager was previously the subject of two citizen complaints, including Givens' complaint, according to city records released by authorities.

Slager was charged with murder after a witness stepped forward with video that appears to show the moment when Slager fatally shot Scott as Scott was running away from Slager. The victim's family attorney, who gave the video to ABC News, said he believes it could prove that the officer used excessive force.

Slager was arrested on Tuesday and has been dismissed from the police department. He appeared at a bond hearing that evening but has yet to enter a plea. Over the weekend, Slager was represented by attorney David Aylor, who said in a statement released at the time that Slager "followed all the proper procedures and policies" but that attorney told ABC News on Tuesday he is no longer representing Slager.