Six officers shot a homeless man 46 times after he failed to follow their instructions in a parking lot.A police investigation into alleged police brutality is underway in Michigan after six officers shot a homeless man 46 times after he failed to follow their instructions in a parking lot.Amateur video captures the fatal exchange between Saginaw police and 49-year-old Milton Hall after he called the police following an argument with a convenience store clerk.Refusing to drop a knife after repeated requests, the video shows officers unleash a volley of bullets at the agitated Hall in a move his mother, Jewel Hall Milton,Shot on July 1st, in the parking lot of West Genessee avenue, the investigation into the use of excessive police force by the officers has taken at least six weeks and caused anger and impatience amongst residents in the town of 50,000 in central Michigan.Police in Saginaw said that Hall had just had a confrontation with a convenience store clerk and in the video the 49-year-old homeless man can be heard to say, 'My name is Milton Hall, I just called 911. My name is Milton, and I'm pi**ed off.'A female officer can be heard to say 'Put the knife down, put the knife down' to which Hall replies, 'I ain't putting sh*t down.'Eventually Hall is seen to move to the left of the frame in the video and then is shot in a barrage of bullets of which at least 30 can be heard to ring out.Officer's of Saginaw Police Department scream at Hall to drop the knife he is carrying but the homeless man refuses to follow their instructionsThe shooting was witnessed by traffic and passers-by.'All of a sudden, pow, pow, pow, pow, pow...and he drops,' said Anthony Baber, who was in his car in the parking lot when the shooting occurred.Saginaw County Prosecutor Michael Thomas said to CNN that the squad of police opened fire 'because apparently, at this point in time, he was threatening to assault police.'The County Prosecutor and Saginaw police have been involved in an investigation into the shooting and Saginaw Police Chief Gerald Cliff said that Hall was 'known to be an assaultive person' with 'a long history' of involvement with authorities, 'not only with police from our department but with the county.'Hall had been jailed for vagrancy in the past said his cousin, Mike Washington, but, 'He was not violent'.Jewel Hall Milton, Hall's mother said that her son was mentally ill and admitted to being furious with police in addition to her obvious distress.Milton Hall (left and right) was 49-years old and homeless. He had spent time in prison for vagrancy and was known to police in Saginaw'It appeared to be a firing squad dressed in police uniforms,' said Milton from her home in Albuquerque, New Mexico.'There was another way. They did not have to kill him. He had not done anything. He was not violent. He was not a murderer. He was not a criminal.'She said that before her son became homeless he was a civil rights activist, received Social Security disability payments for mental illness and had lived in the area for 35 years.Jewel Hall Milton described the shootings as a 'firing squad dressed in police uniforms.''I just don't understand that. It's a lot of pain in that because it only takes one shot, so the question is why?'Distraught, Milton questioned why none of the camera's in the police squad cars were operational.'So that's the question I have and the community has it, what's taking so long?' said Milton.'Why is not being transparent?'CNN asked Lou Palumbo, a former Long Island police officer to examine the footage and he described it as 'a perceptive nightmare'.'This wasn't a scenario where was discharging a weapon in their direction,' said Palumbo.'One of the things the public has to understand, an individual wielding a knife at you at about 20 feet can be on top of you in a split second.'The public doesn't know this because they don't do this for a living.'Saginaw Assistant Manager of Public Safety Phillip A. Ludos said he watched the CNN segment, but declined commenting on the footage.'It's an ongoing investigation and there's possible civil litigation,' said Ludos, who oversees the police and fire departments. 'We've got no statement, one way or another.'