Lloyd Butler should never even have been taken into custody, an inquest jury ruled yesterday.
The 39-year-old father was arrested for appearing to be drunk and incapable, but should have been taken to hospital, jurors said.
Instead, he was locked in a holding cell - and police officers, who were supposed to be monitoring him closely with checks every 15 minutes - returned to their desks.
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Shockingly, CCTV footage released by West Midlands Police show the officers watching porn on a work computer, laughing and swearing.
The hearing was also told that officers made personal phone calls and visited inappropriate websites, including a page where “women were offering sex”.
Mr Butler, in the meantime, had slipped into a cardiac arrest - and was dying in his cell.
Warning: Shocking footage
IPCC Associate Commissioner Guido Liguori, who published the report, said: "The indifferent treatment of Mr Butler by officers and staff of West Midlands Police showed a disregard for both the stated procedures of detention and also for human decency.
"The care given to Mr Butler fell well short of what was expected from when he was arrested to the moment he sadly died.
"Instead of taking Mr Butler to hospital officers kept him in a police cell and instead of helping him, PC Woodcock and DEO Wall mocked him."
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More CCTV played at the inquest showed officers dragging Mr Butler out of a police van by his legs, staggering around his cell and hitting his head against the wall.
Responding to the inquest verdict and the IPCC report, assistant chief constable Gary Cann said:
"On behalf of the force, I would like to take this opportunity to apologise to Lloyd Butler's family."