A man who died moments after being arrested over an incident in the street in Shropshire has been named by police.
Jason Pearce, 38, from Telford, was arrested in Sambrook Crescent, Market Drayton, at about 1730 BST on Saturday following reports of a disturbance.
He collapsed and died at the scene while in the custody of West Mercia Police.
The force said the Independent Police Complaints Commission (IPCC) was also investigating the case.
Officers urged anyone who saw Mr Pearce on Saturday to contact them.
The IPCC said Mr Pearce had been shouting and acting strangely in the street when police officers arrived.
While the officers restrained Mr Pearce on the ground he was found to have stopped breathing, it said.
An ambulance was called but he died at the scene.
A post-mortem examination has been carried out and an inquest will be opened when the results of the post-mortem examination tests are known.
Det Ch Insp Steve Tonks, of West Mercia Police, said: "I am particularly keen to hear from anyone who might have seen Mr Pearce between about 3.30pm and 5.30pm, either before or after the arrival of the police.
"He may have been in the Newcastle Road and Betton Road areas before making his way to Sambrook close and I would again urge anyone who might have seen him there to get in touch."
He described Mr Pearce as a tall, white man, of fairly large build, with short hair.