Update below

Police and prosecutors know who killed Michael Sapp, 33, outside the Charleston on Bedford Avenue in June, but he won't be going to prison anytime soon. Sapp died following an hourlong series of fights in and around the dive bar at North Seventh Street, including one that a witness said involved 30 people, and a final attack that another bystander said "broke [Sapp's] face."

The investigation into Sapp's beating death has now stalled, and the man who delivered the fatal blow, an off-duty bouncer for the Charleston at the time, won't face charges. The Brooklyn District Attorney's Office is leaving the bouncer alone because prosecutors don't believe they could disprove his claim that he acted in self-defense, Homicide Bureau Chief Ken Taub told Sapp's sister, Ampora Yazdani.

Law enforcement officials explained that because Sapp threatened to kill people in the bar when he was initially kicked out, left, and came back threatening people again, the assailant who a witness described running out of the bar and knocking Sapp out without a word could reasonably have acted out of fear for his safety—and the safety of others in the bar.

A spokesman for the DA's Office stressed that the burden of proof is on prosecutors, not the attacker.

"We couldn't prove it was unreasonable for him to throw that single punch," Oren Yaniv said. "The DA must disprove self-defense. The defendant does not have to prove self-defense justification."

Had they decided to prosecute, the most severe charge at the district attorney's disposal would have been third-degree assault, a misdemeanor punishable by a year in jail. That, officials said, is because of New York case law that has been established saying single punches that result in death cannot be considered violent felonies unless the puncher intended to kill or seriously injure the victim.

In this case, the Medical Examiner's Office determined that the bouncer's blow and Sapp's subsequent fall backwards onto his head killed him, according to the officials, ruling out the injuries from previous fights that left him covered in blood, and, according to one witness, "standing unconscious." Asked for clarification on this point, a spokeswoman for the medical examiner declined to go into detail because the investigation officially remains open, saying only that Sapp died of blunt force trauma to the head.

In 2011, prosecutors charged a man named Oscar Fuller with felony and misdemeanor assault after he punched a woman during an East Village parking dispute and she cracked her skull on the pavement, leaving her brain-damaged. The following year, a jury found Fuller guilty only of the misdemeanor, and a judge gave him the maximum sentence of one year imprisonment.

In Syracuse in 2011, a man fatally punched 38-year-old James Huddleston once as Huddleston was arguing with someone else. Found guilty of third-degree assault, David Junious received a one-year suspended sentence with mandated mental health treatment.

A defense attorney said she wished more of her cases were handled as cautiously by prosecutors as Sapp's homicide, but that their message to Sapp's loved ones rings odd.

"It's more responsible to not charge someone who, after investigating, they find they are innocent of whatever charge," said Rigodis Appling, a staff attorney at the Legal Aid Society. "But it's weird to say, 'I think he's going to say [he acted in self-defense], but I don't think I can disprove it.'"

A bill, named Ildefonso Romero, Jr.'s Law after the 58-year-old good Samaritan fatally punched by a 17-year-old while trying to break up a fight, would make it a felony to commit an aggravated assault that results in serious injury or death. It passed the state Senate in June and is before the Assembly's Codes Committee, but wouldn't have affected Sapp's case given prosecutors' deference to the bouncer's self-defense claim.

Yazdani, Sapp's sister, has complained from the beginning that the investigation was dragging, and she is dismayed by the latest development. Because Sapp was standing outside the front gate of the Charleston when the attacker laid him out, she argues there could be no justification for coming outside in the first place.

"The person that came out and dealt the one punch, there was no reason for him to come back outside the bar," she said. "Mike was outside the bar. He didn't come back in the bar. The guy came outside the bar and had no business doing that."

Sapp was unarmed. After knocking him out, the bouncer "was jumping around and laughing," according to a witness. "You shoulda not fucking come back," he gloated. "I told you, you're asking for it." Within a few minutes, at the prodding of his friends, the bouncer climbed into a black SUV with New Jersey plates and drove off, according to witnesses. Law enforcement sources said how long the bouncer spent outside before decking Sapp and whether he fled the scene did not factor into the decision not to prosecute, and they noted that he later cooperated with detectives.

A manager for the Charleston sought to distance the bar from the bouncer's actions, emphasizing that he was off-duty, and that he was hired on a temporary basis.

"The 'bouncer' that struck Micheal Stapp [sic] was not working at any time that night," David Slifkin said in an email. "He was at the Charleston on his own time and was not representing the Charleston when he interacted with Mr. Stapp [sic]. The 'bouncer' had worked less than a dozen times as a temporary fill-in (licensed) security guard for the Charleston."

The State Liquor Authority fined the Charleston in January for employing an unlicensed bouncer. Slifkin said Sapp's assailant "has not been seen at the Charleston since." He declined to identify the bouncer, and did not respond to an inquiry about his previous pledge to provide "full access to the witnesses and my staff" once the investigation ended.

Sapp grew up in the New York area, but had been living in Los Angeles until last year. He moved back to be near his teenage daughter as she began high school, and though he held down a steady job at The Bagel Store in Williamsburg, he struggled with alcoholism and was in and out of homeless shelters. Friends said that in the weeks leading up to his death, he had been living in a park. He recognized that he had a problem, though, and had identified rehab programs to enroll in, according to a close friend. He had a religious side, too, the friend said, and hoped to one day open a church in Los Angeles.

None of that came to be. In addition to the lack of action by law enforcement, Yazdani is upset that over the course of an hour on Bedford Avenue on an especially busy Saturday night, no one stepped in to defuse the situation. One witness described the bar-goers who packed the Charleston's front seating area that night turning away after the bouncer sent Sapp sprawling, hoping to avoid being attacked themselves. Then, after the man left, they pulled out their phones to photograph Sapp as he began coughing up blood.

"I'm dumbfounded by the fact that this could go on in a public place that there was really no intercessory force, for real," Yazdani said, sounding tired of rehashing the terrible events of that night. "It is what it is."

Update August 14th:

Charleston manager David Slifkin disputes the NYPD's assertion that fights occurred "inside and outside of the bar," saying that all the violence occurred outside.

He explained in an email:

"[Sapp] was removed from the bar with minimal guiding force (no pushes, no punches), simply a hand on his shoulder."

In addition to contradicting the police account, Slifkin's claim goes against a witness interviewed on June 17th, who said that a bouncer was "verbally jousting" with Sapp inside the bar around 11:30 p.m. The witness recounted the bouncer saying Sappp had to leave because he was too drunk. The witness said that the bouncer shoved Sapp, he punched back, and the bouncer started "piling blows" on him before getting him out the door.

Slifkin also provided more of a picture of the bar's version of the night's events in a series of emails:

After he got outside the bar, Mr. Sapp became sociopathic, threatening, violent and began to fight several people, none of which were employed by the Charleston that night.

Did you ever request or receive a toxicology report to see what might have triggered Mr. Sapp's anti-social, violent behavior? [Note: The Medical Examiner's Office does not provide toxicology information unless it factors into the cause of death.] It certainly wasn't the 1oz of whisky and 16oz of beer he consumed at our bar.

[Inside, Sapp] was saying that he could not find his bag. He was freaking out. Pacing back and forth talking / mumbling to himself with curse words and threats. My inside bouncer helped him look around with his flashlight several times, they looked everywhere that Mr. Sapp said he had been (and everywhere else they could think to look). After enduring quite a bit of verbal abuse from Mr. Sapp, and Mr. Sapp was refusing any kind of reasonable assistance (Mr. Sapp stopped letting us help him look ), it was time for Mr. Sapp to go. And, fortunately, we got him outside without a struggle.

After watching the video tapes with the detectives, we learned that Mr. Sapp himself had hidden his bag, underneath the mezzanine staircase and behind a garbage can. You can see Mr. Sapp begin to panic on the video tape less than 10 minutes after he stashed his bag. Tragic.

Slifkin suggested consulting Sapp's criminal record, which law enforcement officials provided to DNAinfo early on in the investigation, and he concluded an email by writing, "The Charleston did nothing wrong that night, sorry if that doesn't generate clicks and page impressions."