THE death of a man in police custody may have been a possible murder that was overlooked, a court has been told.

Antony Storrie died just a few months after the creation of Police Scotland and its new watchdog in April 2013.

Now a hearing has been told that confusion over remits under the new regime may have led to serious failures in the investigation.

Mr Storrie, who was arrested shortly before his death, was initially believed to have died from a legal high overdose, but a post mortem revealed he had suffered a "blunt force trauma".

While he showed no external injuries, experts are expected to tell a Fatal Accident Inquiry (FAI) that the trauma was the equivalent of Mr Storrie being jumped on from a height.

The 25-year-old's case was the first death in custody investigation carried out by the Police Investigations and Review Commissioner (Pirc).

Solicitor Peter Watson, who represents one of the arresting officers in the case, said: "The Pirc had just been set up and had just started operating about this time and it may well be that some of the criticism which will emerge, either in respect of the Pirc or Police Scotland, may be to do with confusion as to their respective roles.

"It seems likely to me that the nature and extent of that Pirc investigation will be criticised."

He added that the inquiry will also look at the police investigation and draw on the expertise of a retired senior officer who will give evidence on the force's "murder investigation manual" which was in place at the time.

"The murder investigation manual, I'm told, is effectively the bible used to investigate suspicious and unexplained deaths," Mr Watson said.

"I'm also told by this expert that certainly at the point of the post mortem declaring that the death was brought about by blunt force trauma, this would have required the murder investigation manual to be followed.

"It appears from what has been disclosed in this case that that manual was not followed and the investigations that ought to have been taken have not been taken."

Mr Storrie was believed to have taken a cocktail of legal highs, including the psychoactive and now-banned N-bomb substance, at a party in his Paisley flat on June 30 2013.

He was arrested for alleged "aggressive behaviour" before being taken to hospital where he was pronounced dead the next day.

Mr Watson claimed that, because of the passage of time, it may now be too late to discover exactly what happened to him.

The lawyer said: "I suspect at the end of this inquiry we're likely to still have an unexplained death because the opportunity to do what required to be done in terms of this man's death, in many instances, will be gone because of the need to capture evidence contemporaneously.

"The opportunity for forensic evidence from those present in the flat has gone. The clothes that were worn by the deceased are in a bag in a Paisley police office and in the absence of a forensic report, I'm presuming that these haven't been forensically examined."

He added: "I think what we may find is that there have been failures and because of those failures, a loss of evidence, and that loss of evidence may hamper the inquiry from reaching a conclusion."

Mr Watson said he would be writing to the procurator fiscal to request that they ask Police Scotland to review the case. He also asked the court to notify the PIRC so that they can decide whether or not to instruct legal representation in the inquiry.

A Police Scotland spokesman said: "We are aware of the comments made at the preliminary hearing and they will be considered. It would, however, be inappropriate to comment further at this time."

The FAI will take place at Paisley Sheriff Court in August.

The Pirc declined to comment as the inquiry is ongoing.