The family of a musician who died in custody said they hoped that criminal charges would be brought against officers as they welcomed the reopening of an investigation in to his death by the police watchdog.
Schizophrenic Sean Rigg, 40, died in August 2008 while he was being held at Brixton police station after being arrested for attacking passers-by and police officers in Balham, south London.
Today the Independent Police Complaints Commission (IPCC) announced it has reopened its investigation, which will look at the conduct of the officers involved in the arrest, restraint and detention of Mr Rigg and the actions of the force medical examiner at Brixton police station.
Last year the inquest into his death found that officers had used "unsuitable force", and earlier this year a review set up by the IPCC to re-examine its own investigation into Mr Rigg's death, led by criminologist Dr Silvia Casale, found that the watchdog should look again at whether police officers should face misconduct proceedings for the way they dealt with him.
The IPCC's original investigation was slammed by Mr Rigg's family as "extremely poor and ineffective".
"We will accept nothing less than for this new investigation to be robust, transparent and properly effective," Sean's sister Marcia Rigg said.
"It is over five years since Sean died and we therefore expect the IPCC to devote the necessary resource to ensure an early outcome to their new investigation.
"No family should ever have to go through the burden of losing a loved one in police custody and then find that the legal system fails them time and time again.
"We hope that the compelling evidence will lead to criminal charges against the officers involved in Sean's arrest, restraint and detention and ultimately his death."
The IPCC investigation will determine whether to recommend any disciplinary proceedings against the officers, and whether there is evidence that should be considered in relation to potential criminal proceedings.
IPCC Commissioner Mary Cunneen said: "During the course of the review we have identified additional lines of enquiry that need to be investigated, so that we can assess whether to make a referral to the Crown Prosecution Service regarding potential criminal matters or recommend disciplinary proceedings regarding any officer involved in the arrest, restraint and detention of Mr Rigg.
"I have consulted with Mr Rigg's family, the officers involved in the arrest, restraint and detention of Mr Rigg, the Metropolitan Police Service and the forensic medical examiner that I was minded to reopen the investigation and last month informed them that we have now done so.
"I appreciate that it has now been over five years since Mr Rigg's death and that his family, the officers involved and the FME will be anxious that we proceed as quickly as possible.
"Having taken the decision to reopen the investigation, the team has already begun to recover and analyse evidence and will be obtaining further statements from a number of people.
"The reopened investigation will, like the review, only examine the conduct of the officers involved in the arrest, restraint and detention of Mr Rigg and the actions of the forensic medical examiner who attended Mr Rigg at Brixton police station."
The IPCC said it has been informed that Scotland Yard plans to seek a judicial review of the decision to reopen the investigation - not because it opposes it, but because it believes the findings of the original investigation first need to be quashed by a court.
The watchdog said: "The IPCC considers that it is acting lawfully, but will consider the representations of the MPS carefully and respond in due course."
In a statement, Scotland Yard said it was "fully supportive" of the IPCC's plan to reopen the investigation provided the "legal obstacle" was removed.
It said: "Following the inquest into Mr Rigg's death and the Casales' Review the MPS (Metropolitan Police Service) accepts that the first IPCC investigation was of an inadequate standard.
"The MPS also accepts that the findings of the inquest jury, with its recorded narrative verdict, was at variance with the IPCC's initial report and therefore creates the need for further investigation and greater clarity."
The statement said after receiving legal advice, the force believed the original IPCC decision first needed to be quashed and it had assured the watchdog that it would not oppose any application for a quashing order, but said the IPCC had advised it planned to re-investigate without a quashing order.
"In view of the position taken by the IPCC the MPS has therefore had no choice but to write to the IPCC to advise of its intention to judicially review the IPCC's decision to re-open the investigation without first seeking the necessary quashing order," the force said.
"The MPS has invited the Commission not to oppose this application and, exceptionally, has offered to pay their legal costs on this basis.
"This is in order to keep delays to a minimum in deference to the impact this could have on the family of Mr Rigg. We await their reply.
"The MPS has consistently made it clear that it will cooperate with a lawful IPCC re-investigation into some or all of the circumstances leading to Mr Rigg's death.
"Our thoughts remain with the family of Mr Sean Rigg and we understand their desire to search for answers following his death.
"What remains important is that despite the legal difficulties, those answers can be found in a way that complies with the law."
As part of a separate inquiry, two serving police officers and one former officer were arrested in March over allegations around evidence they gave to Mr Rigg's inquest.
The two serving officers were arrested on suspicion of perjury and perverting the course of justice and the retired officer on suspicion of perverting the course of justice.
An IPCC spokeswoman said: "The IPCC investigation into evidence given at the inquest into Sean Rigg's death is complete and an investigation report is being finalised. The Commissioner will then make a decision on whether to formally refer the matter to the CPS.
"Two serving MPS officers and one retired MPS officer have been released from bail as all investigative steps have now been completed. This is not an indication that no further action is being taken."
Deborah Coles, co-director of INQUEST, said: "It took four years for the family to hear the truth at inquest of how Sean died.
"It then took a further nine months for an independent review to vindicate their concerns about the IPCC investigation that was so at odds with the evidence heard at inquest.
"And now, six months later, the IPCC has finally announced it is to reinvestigate his death.
"The IPCC must move quickly and ensure an effective and thorough new investigation.
"It is absolutely imperative that this family is not forced to endure any more long delays. Delayed justice is in nobody's interest.
"Such delays in holding the state to account for potential criminality and wrongdoing as a result of a flawed investigation must not happen again."