On Monday a grand jury convened to decide if a white police officer should be indicted in the shooting of an unarmed black man.

But the jury isn't meeting in Missouri, and the young man who died wasn’t named Michael Brown.

On Aug. 5, four days before 18-year-old Brown was shot dead in Ferguson, Missouri, local police shot 22-year-old John Crawford III while he shopped at a Walmart near Dayton, Ohio. Police have said officers thought the pellet gun he held was a firearm, and acted quickly and appropriately to protect customers. His family said something went terribly wrong.

“Somebody’s going to have to explain to me how anybody goes into Walmart and ends up dead,” said John Crawford Jr., the dead man’s father. “It appears that we have an epidemic in the United States of America where young black men are being slain by white police officers, and nothing is being done about it. And we need to stop that now.”

On that warm summer night, Crawford III walked into the Walmart in Beavercreek, an upscale Dayton suburb with a population of 45,000, less than three percent of it black. His family says he went to the Walmart to shop for the cookout he was going to attend that night. They say that as he shopped, he talked on his cellphone with LeeCee Johnson, the mother of his two baby sons.

In about six minutes of soundless surveillance video shown by state officials to the young man’s father and an attorney for the family in late August, the family says they can see Crawford III, via footage apparently cut together from more than one store camera, walking through the Walmart aisles as he talks on his cell phone. NBC News has not seen the tape, but the family says Crawford III stops in the sporting goods section and picks up an unboxed Crosman MK-177, a pellet gun that’s designed to look like a real assault rifle. Then he wanders into the pet section carrying the pellet gun, still on his cell. (The Beavercreek Walmart also sells real assault rifles.)

“He just walked around the store with it, just like any shopper would do,” said Crawford Jr., the man’s father, who is a former parole officer. “There were people passing him by. You could see on the video there was no alarm at all.”

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But one person in the store was concerned. At about 8:21 p.m., Ronald Ritchie, who is 24 and white, called 911. On recordings released by the Beavercreek Police, he tells the 911 dispatcher a man is “walking around with a gun in the store...like, pointing it at people.” As police begin to mobilize, Ritchie tells the dispatcher that the man, whom he describes as black and about 6 feet tall, with an “Afro,” is “like loading [the gun] right now” and “waving it back and forth.” Four minutes into the call, Ritchie says, “He just pointed it at, like, two children.”

Listen to Ritchie's 911 Call

By that time, Officer Sean Williams and Sgt. David Darkow were already on the scene, according to a statement released by Beavercreek Police on Aug. 6. They moved to the pet section, at the back of the store, where they confronted Crawford “holding a rifle,” the statement said.

“Officers gave verbal commands to the subject to drop the weapon,” the statement said. After he failed to comply with officers’ commands, police said, he was shot.

People gather in a parking lot to support the Beavercreek Police Department in Beavercreek, Ohio, on Aug. 30. Some 200 people held signs and chanted outside a Wal-Mart where a young man with an air rifle was fatally shot by police. Darin Pope / The Dayton Daily News via AP

Crawford Jr. said that in the minutes before his son was shot, the video shows the young man standing facing a shelf, talking on the phone and leaning on the pellet gun, barrel down, like a cane. He is standing so still, the father said, that it looks like the video has stopped. Then the feet of two police officers come into the lower corner of the silent screen, he said. Crawford III is still partly facing away from where the officers are standing, his father said. The tape has no sound, but Crawford III does not seem to react to any sort of sound, like the commands to drop the weapon that the police said were yelled.

At 8:26 pm, about five minutes after Ritchie called 911, John Crawford III tumbled to the ground.

LeeCee Johnson, the mother of Crawford III’s children, was sitting outside his mother’s house talking to Crawford III on the phone when she heard the sound of gunfire come over the line. Her children were inside playing with their grandfather, Crawford Jr.

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“As I was playing with them, I hear this scream [from Johnson],” remembered Crawford Jr. “‘Mr. John, Mr. John they shot him! He’s calling your name!’”

Crawford Jr. said Johnson put the cellphone on speaker and the family listened as his son gasped for breath.

In the surveillance video, “You can see my son lying flat on the ground,” said Crawford Jr. “And you can see him like a fish out of water, moving a little bit.” Then, said Crawford Jr., the tape cuts out.

The shots sparked chaos in the store. Ritchie was still on the phone with the police dispatcher, and screams and a wail can be heard on the tape of the 911 call. “Sir, what’s going on?” the 911 dispatcher asks. “Shots fired,” he responds.

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Customers began to stream out the front doors, captured by the cameras in the police cars that arrived as backup. Several people on the scene called 911, including workers in the Walmart pharmacy, who barricaded themselves in a bathroom at the sound of gunfire. Angela Williams, a 37-year-old customer with a heart condition, collapsed trying to get her children out of the store, and died soon after.

Listen to a 911 Call After the Shooting

Crawford III was rushed to Miami Valley Hospital in Dayton. He was pronounced dead at 9:23 p.m. from a gunshot wound to the torso, according to the Montgomery County Coroner. The manner of death was ruled to be homicide.

Crawford Jr. identified his son’s body the following morning. Later, at the funeral home, he said he unzipped the bag to look at his son’s body before it was buried. He counted six holes in his son’s body that he believed were left by the entry and exit wounds of two bullets. One bullet apparently ripped through an arm, then went into the torso, exiting through the back. The second bullet tore through the other arm.

The Beavercreek Police declined to comment to NBC News about the accuracy of Crawford Jr.’s description of the tape. A spokesperson said officers on duty that night had seen some footage from one camera, but not the compilation of footage provided to Crawford Jr. and his attorney, before the footage was handed over to state authorities now conducting the investigation.

“The quick response of officers was instrumental in containing this situation and minimizing the risk to customers,” wrote Beavercreek Police in the department’s Aug. 6 press release. “Preliminary indications are that the officers acted appropriately under the circumstances.”

The Beavercreek city attorney also declined to offer further comment.

In an effort to ensure transparency, Beavercreek handed the investigation of the shooting over to Ohio Attorney General Mike DeWine’s office, which oversees the Ohio Bureau of Criminal Investigation, now conducting the probe. BCI has reportedly interviewed a number of witnesses, including Ritchie, the man who called 911.

In the weeks since the shooting, questions have been raised about Ritchie’s credibility. Following the shooting, Ritchie told two local reporters Crawford III had pointed the gun at children in the store. But in an interview with the Guardian newspaper in early September, he said “at no point did he shoulder the rifle and point it at somebody,” though he maintained Crawford III was “waving it around.”

When the Guardian challenged Ritchie on his assertion that he was a former U.S. Marine, Ritchie reportedly admitted he spent just seven weeks in the Marine Corps in 2008 before being declared a “fraudulent enlistment.” He said it was due to a mix-up in his paperwork over whether or not he had disclosed a heart condition. NBC News has confirmed that Ritchie was in the Marines from Sept. 8, 2008 to Oct. 31, 2008.

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But what most concerns Michael Wright, the Crawford family attorney, are Ritchie’s claims to the Guardian that officials had shared with him both the surveillance video and details of Crawford III’s criminal history. According to his father, the dead man’s record includes a few misdemeanors but no felonies.

“If they did show him any information, we believe that is highly inappropriate,” said Wright, who believes that it could taint Ritchie’s witness testimony. He adds that Ohio is an “open carry” state, and that even if the pellet gun Crawford III was holding had been a real firearm, it would have been within Crawford III’s right to carry a rifle in the Walmart without a permit as long as it was in view.

Attempts to reach Ritchie were unsuccessful -- the phone number he provided to police has been disconnected. Attorney General DeWine’s office declined to comment on questions about what Ritchie had been shown, or on the accuracy of Crawford Jr.’s description of the surveillance tape.

DeWine’s office directed all questions to Hamilton County Prosecutor Mark Piepmeier and Stacey DeGraffenried, who have been appointed special prosecutors on the case. On Sept. 22, they will present evidence to a special grand jury in Greene County in proceedings expected to take several days. A spokesperson for Piepmeier declined to answer any additional questions about the case.

Wright and the media have speculated that evidence will be presented against Officer Sean Williams, who remains on administrative leave. Sgt. Darkow has returned to duty.

Left: Beavercreek Police Officer Sean C. Williams; Right: Beavercreek Police Sgt. David M. Darkow via Dayton Daily News

In 2010, as the Dayton Daily News reported, Williams was involved in another fatal shooting -- the only other in the Beavercreek department’s history. When officers responded to a domestic violence call, an apparently intoxicated man inside the home allegedly lunged at officers with a kitchen knife. Williams shot the man, and he died. A Greene County grand jury declined to bring charges against Williams for the shooting.

The next year, Williams was reprimanded for “unbecoming conduct,” according to his personnel file, for his language and behavior during a different incident. His file also includes a number of commendation letters for jobs well done, and in his 2013 review his “good judgment” in emergency situations was noted. His father is also on the 47-member police force.

An attorney for Williams and Darkow said the officers followed procedure -- they called back to dispatch to confirm Crawford III had a weapon, and that it might be loaded. Upon arriving, they ordered Crawford III to drop the gun, and fired only after he did not do so.

"The officers acted well within their training," said Vincent Popp. "I think it's a tragic situation but the officers did nothing criminally wrong."

To Crawford Jr., justice for his son means an indictment of the officer, or officers, who shot him. But it also means transparency, he said. He wants people to see the video from inside the Walmart store, which the attorney general has declined to release, citing the ongoing investigation. And he wants people to admit that something went wrong in that aisle that day because only then, he said, can there be efforts to fix it.

“If the lawman breaks the law, there is no law,” he said. “As tragic as my son’s death is, maybe just maybe if there was some integrity in this situation I could better digest it. Right now I can’t digest it.”