A charity campaigning on behalf of the families of those who have died in police custody in the U.K. are warningthat the latest independent investigation could be just another PR exercise.

The probe was announced hours after statistics from the Independent Police Complaints Commission (IPCC) revealed that such deaths have reached a four-year high. Seventeen people have died in or following detention by police in 2014-15, an increase of six from the previous year and the highest since 2010-11, when 21 people died.

On top of these figures, the campaigning charity INQUEST has also pointed to separate, troubling findings revealing that 250 young people aged between 18-24 committed suicide in custody between 2010-2015.

Home Secretary Teresa May launched the investigation on Thursday afternoon after a series of high profile cases and allegations of wrongdoing. A meeting with INQUEST and the families of Sean Rigg andOlaseni Lewis, who both died after being restrained by police officers, prompted the Home Secretary to declare a desire to “solve  significant problems for those fighting for justice following the deaths of relatives.”

Responding to the launching of the review, Deborah Coles, Co-Director of INQUEST, said, “For the review to be effective bereaved families, their lawyers and INQUEST will need to play an integral role in the review, and the Reviewer will need to take full account of their views and experiences. It must also address why so many previous recommendations from reviews, inquiries and inquests have not been acted upon. It is too early to tell if this is more about a public relations exercise than a real attempt to bring about effective systemic change and the necessary accountability of police officers.”

In her blog for the Huffington Post, Marcia Riggs, mental health activist and Sean Rigg’s sister, described her brother’s treatment in custody. “The cops treat the mentally ill like criminals. Even in patient wards, Tasers and prolonged prone restraint are used to subdue patients. The latter more than minimally contributed to Sean’s death, the inquest jury found. As his body laid lifeless and unresponsive, the custody sergeant insisted he was ‘feigning unconsciousness’. [sic] Sean was assumed guilty, even in his death.”

In their tireless campaigning to change policies and practices related to deaths in custody in the U.K., INQUEST has collated shocking figures revealing over 4,500 deaths in prison and police custody in England and Wales between 1990 and 2013.  The investigation will examine the procedures and processes surrounding such incidents, including the events leading up to them, the immediate aftermath, and through to the conclusion of investigations.

The charity describes patterns of institutionalised reluctance to approach custody deaths as potential homicides, even where there have been systemic failings and gross negligence. Many of the deaths also raise serious issues about a failure to care for the vulnerable in a system where institutional violence, racism, inhumane treatment and abuse of human rights are recurrent themes.

In response to the announcement of the review, Ajibola Lewis, mother of Olaseni Lewis, said, “For our part, we are surprised that the proposed review, its purpose and its scope is being announced without any prior consultation with us or other families in our position.  If the review is going to be more than an exercise in public relations, and if it is to enjoy the confidence of families in our position, it must find a meaningful way to learn from and reflect our experiences. We find deep seated and repeated failures on the part of all of the agencies of the state to whom we look to take responsibility to investigate and prevent such deaths, including those concerned within the senior management of our police service, the Independent Police Complaints Commission, the Crown Prosecution Service and the Coroners Courts.”

She added, “…we find that these agencies of the state do not seem to understand that if they listen to us, if they enable us to take part properly in the process, they would allow us to help them achieve a more effective investigative process and more effective outcomes – that this would be in the best interests of all concerned, families as well as the officers whose actions resulted in the deaths of our loved ones.”