Bedfordshire police will not face criminal charges in relation to the death of Leon Briggs in November 2013.
The 39-year-old was restrained by officers at Luton police station while being held under the Mental Health Act. He later became ill and died in hospital.
His mother said she is "devastated" no charges will be brought.
Five officers and one member of Bedfordshire Police were investigated.
And The Crown Prosecution Service had considered corporate manslaughter charges against the force itself.
However, the CPS said there was not enough evidence to bring a prosecution. They had already dismissed charges against one officer earlier this year.
Leon's mother Margaret Briggs said she's been left devastated by the decision:
Jocelyn Cockburn of London solicitors, Hodge Jones & Allen represents Mrs Briggs. She was also critical of the decision:
Bedfordshire Police issued this statement over the decision of the CPS
"The CPS announced it would be taking no further action against any officer in relation to the death of Mr Briggs in November 2013.
" Mr Briggs died in hospital after being detained at Luton Police Station. Today's announcement was in relation to five officers - a further officer had already been cleared of any criminal wrongdoing in March and a detention officer was cleared in 2014.
Bedfordshire Chief Constable Jon Boutcher said: "We are aware of the CPS decision not to bring any criminal charges against any of the officers involved in this case.
"It has taken almost five years to reach this position and that is simply unacceptable for all concerned. This long overdue decision will no doubt bring painful memories for Mr Briggs' family and friends and they should always remain in our thoughts. It is, to say the least, disappointing that the investigation by the Independent Police Complaints Commission (IPCC) took the time that it did to get to this point. I have dealt with many complex matters that can understandably take some time to investigate especially with the need to recover evidence and to identify witnesses particularly when a matter is complicated. However this tragic death is not such a case.
"All of the people around the event were identified immediately and much of the activity was captured on CCTV. How on earth has this taken so long? The time taken has put added strain on Mr Briggs' family, and, please let us not forget, the officers involved. I am hoping significant lessons are learned from this by the Independent Office for Police Conduct (the successor to the IPCC).
"Bedfordshire Police continues to look at how we can improve our knowledge of and response to dealing with vulnerable people. As more police demand than ever is linked to mental health challenges in society I am determined, as are all chief constables, to make sure we learn the lessons of incidents such as this. I am also clear that the officers involved are not forgotten. We cannot have officers suspended for five years or more when the circumstances of an event are not complex.
"This case is an example of why processes need to improve in the interests of those who believe the police have acted criminally and for the officers themselves."