Police are appealing for witnesses to come forward after a man who was detained by member of the public died following a suspected robbery in Wolverhampton.
Officers received a 999 call just after midnight on Sunday 16 October reporting that a bag had been snatched from a woman in Stafford Road, Oxley.
Two men who witnessed the crime had detained a man, and were asking for police to attend the scene.
Officers arrived and arrested the 29-year-old, who then became unwell, and officers performed CPR until paramedics arrived and took over.
The man was taken to hospital but died on Wednesday 19 October.
Detective Inspector Greg Evans, from Wolverhampton CID, said: "We are piecing together what happened on Sunday and it is really important that people who were in the area at the time come forward.
“We know the man who made the original 999 call asked a passing member of the public to help him confirm the location as he was unsure.
"That passer-by then spoke to the 999 operator but left the scene… I really need him to contact me or one of my team so I can clarify what he witnessed.
"I am also interested in speaking to an elderly couple that were seen walking along the street at the time of the incident."
He added: "There were also a number of cars that would have passed the location and I would like the drivers and passengers to come forward too."
Enquiries into exactly what happened on the Sunday are ongoing, and further tests are required following a post mortem examination.