Faruk Ali who lives in Luton, Bedfordshire was according to his family, abiding by his weekly routine of helping the bin men with their rounds when the alleged unprovoked attack happened on February 20.
The officer responsible has been put on restricted duties pending investigation.
A meeting between the family and the police this week.
Musthafa Hussain told BBC Look East he saw the incident.
“They dragged him, they punched him, they held him hard,” he said. “It was outrageous.”
Bedfordshire Police said the force was
“sorry for the distress Mr Ali and his family feel regarding the actions officers took due to their concerns for Mr Ali’s wellbeing”.
“This incident is being taken seriously and an investigation has been launched by the Beds, Cambs and Herts Professional Standards Department which will be supervised by the IPCC.”
National Autistic Society’s Policy and Participation Officer Tom Purser said:
People with autism have difficulties with social communication and can become extremely distressed in situations that they do not understand or when they are surrounded by noise and confusion.
‘In such circumstances, their actions and behaviour can easily be misinterpreted and situations can quickly escalate.
‘It’s essential that everyone involved in the criminal justice system, from police officers and prison staff to High Court judges, has access to autism training so they can familiarise themselves with the condition and its complexities.’