Relatives of a father of three who died after being restrained by up to five police officers during a drugs search have reacted with fury as prosecutors decided not to bring charges in the case.
However the officers, from Thames Valley Police, could face the sack as watchdog the Independent Police Complaints Commission (IPCC) found a case to answer over alleged gross misconduct.
Evidence has also been passed to the Solicitors Regulation Authority relating to a Police Federation lawyer who instructed them.
Habib Ullah, 39, was forced to the ground in a car park in High Wycombe on July 3, 2008 by police who believed he was hiding class A drugs in his mouth.
At the inquest into his death in 2010, his girlfriend Emma Forbes told the court that up to five officers restrained him as they tried to force the package out of his throat, including one officer who shouted "break his arm".
The inquest was abandoned after concerns were raised about differences between statements the officers had given to the coroner, and what they had previously told the Independent Police Complaints Commission (IPCC).
Today Mr Ullah's sister Nasrit Mahmood said: " We are not happy that the CPS has decided not to charge those police officers who are responsible for Habib's death.
"A healthy man dies at the hands of the police within minutes. Then at the inquest they are caught out withholding evidence in front of everyone including the judge and jury; we have evidence of police cover-ups, so not only is it my opinion that they caused my brother's death but these police officers have not given a full and truthful account. How on earth can CPS disregard the facts?
"This sadly shows that the CPS together with the IPCC are only there to protect and cover up police crimes. Their decision has only shown their true colours but made us much stronger. This is not justice for us and we will not give up until justice is served and that is a promise."
Five police officers and their solicitor were all interviewed under caution and in February last year the Independent Police Complaints Commission passed a file to the CPS.
IPCC associate commissioner Guido Liguori said: "This has been a complex investigation which as we have said has taken an unbearably long time for Mr Ullah's family. I am very sorry for the prolonged distress this has caused, but it has been essential to ensure that our investigation was robust and thorough."
The watchdog has passed details of its investigation to the coroner ready for an inquest.
The family's solicitor, Marian Ellingworth said: " This is a very disappointing decision. The family have displayed great dignity and waited patiently for nearly four years since the inquest was adjourned in December 2010 only to be told there will be no prosecution.
"In my view, it exposes the failure of the criminal justice system to hold police officers to account and urgent reform is required, in particular of the manslaughter offences, so that the threshold for bringing prosecutions in such cases is more achievable.
"I will be advising my clients about potential remedies open to them and we will be meeting with the CPS and seeking a full explanation for their decision making.
"I am also very disappointed that the CPS has failed to charge the officers and solicitor for the significant changes made to their statements and only admitted at the inquest. Such conduct by public servants under a duty to conduct themselves with integrity is highly reprehensible and it is to be regretted that the CPS does not consider that there is sufficient evidence to charge."
The CPS said it had considered the possible offences of manslaughter by gross negligence, misconduct in public office, perjury and perverting the course of justice, but that there was insufficient evidence to prove any crime.
A spokesman said: "We carefully examined the evidence in this case, including evidence provided by experts in pathology, emergency medicine and policing techniques and accounts from eyewitnesses. We also sought the views of an experienced Queen's Counsel.
"Since there is insufficient evidence to give rise to a realistic prospect of convicting any person of any criminal offence arising from the circumstances of Mr Ullah's death, we have advised the IPCC that no further criminal action should be taken.
"Our thoughts remain with Mr Ullah's family at this difficult time for them and we fully understand that this is not the decision they will have wanted. We have written to them to explain our decision in detail and have offered to meet with them to discuss this matter should they so wish."
Thames Valley Police said the officers were being investigated because of information they left out from statements given to the IPCC.
A spokeswoman said: "This is an internal discipline matter. It relates to the five officers allegedly leaving out materially significant details from the statements they submitted to the IPCC investigation and for subsequently failing to correct these omissions.
"In addition, Thames Valley Police has found that there is a case to answer for one of the officers in relation to the use of force during the drugs search conducted on Mr Ullah on July 3 2008.
"This matter will now proceed to a misconduct hearing and it would be inappropriate to comment further until this is concluded."