FIVE Oxford police officers have been warned they may have breached behavioural standards after a 25-year-old died while being taken to custody.

An investigation into the death of student Nuno Cardoso – who died in hospital after suffering a cardiac arrest in the back of a police van last year – is “nearing its conclusion”, according to the Independent Office of Police Conduct.

The developments in the investigation came as Craig O’Leary, chairman of Thames Valley Police Federation, lambasted the IOPC for treating officers involved in investigations like “criminals”.

Mr Cardoso was being taken to custody in Abingdon in the back of a police van after being arrested for assault when he suffered a cardiac arrest at around 5.30am on November 24.

Officers stopped the van at the entrance to Redbridge Park-and-Ride, in Abingdon Road, in order to administer CPR.

Additional officers arrived at the scene with a defibrillator and provided further medical assistance.

He was taken by ambulance to the John Radcliffe Hospital in Oxford where he died later that day.

Spokeswoman for the IOPC Julia Davies said: “We are awaiting the final post mortem report and expert evidence. All other lines of inquiry are complete. Five officers have been informed their conduct may have breached the standards of professional behaviour.

“This does not necessarily mean that misconduct proceedings will follow.”

Federation chief for the region Mr O’Leary recently attacked the IOPC over the time it spends on investigations and its lack of communication.

A new report shows that the IOPC is taking 233 working days on average to sort out complaints.

Mr O’Leary said: “If the IOPC could come and explain the delays to us, that would help. We all accept that things happen, things don’t move quickly.

“But I’m not convinced that’s the case at the moment, there just seems to be a lot of untimeliness.

“If police officers were out there investigating crime, we have timelines in terms of keeping victims updated, there’s the victim contract that we enter into. And yet the IOPC are very much focussed, and rightly so to an extent, on a victim’s family and communicating with them, I think that sometimes that’s to the detriment of the police officers that are subject to or involved in the investigation.

“They are being treated like criminals effectively and I find that wholly inappropriate.”

IOPC spokesman Sarah Pitt said: “We would welcome the opportunity to discuss Mr O’Leary’s concerns directly with him. As Michael Lockwood, our new director general, told the Police Federation Conference earlier this year, improving the timeliness of our investigations is a priority for the IOPC.

“We are now close to achieving our target of completing 80 per cent of independent investigations within 12 months, and within that will be a proportion closed within three and six months. We are also reliant on other agencies and the cooperation of police officers themselves.”