Media playback is unsupported on your device Media caption The BBC Disclosure programme features previously unseen footage

New evidence uncovered by BBC Scotland has raised fresh questions about the way police officers treated a man who died in their custody.

Fife father-of-two Sheku Bayoh, 31, died in 2015 after being restrained by police in Kirkcaldy.

CCTV, other footage and documents obtained by the BBC casts doubt on some of the officers' accounts of the events that led to the death.

Police Scotland said they could not comment while the case was ongoing.

A BBC Disclosure programme screened on Monday night featured:

Evidence the first officers on scene escalated the situation instead of trying to defuse it

CCTV footage which questions officers' claims a female officer was kicked and stamped on by Mr Bayoh

Evidence that Mr Bayoh's actions were exaggerated in official police documents

Claims that racism may have played a role in the events

'We want to know how he died'

Image caption Thirty-one-year-old Sheku Bayoh died in 2015 after being restrained by police in Kirkcaldy

In October, Mr Bayoh's family were told by the Lord Advocate there was not enough evidence to prosecute any of the officers involved. The Crown Office has not confirmed the decision publicly, and says the case remains open.

Mr Bayoh's family are likely to ask for the decision to be reviewed but are now calling for a full public inquiry.

His sister, Kadi Johnson, said: "We are still here suffering, his boys are suffering.

"There was no need for Sheku to have died that day. We just want to know how our brother died, that's all."

On the day he died, Mr Bayoh had been at a friend's house in the morning watching a boxing match. He had taken the drugs MDMA and another drug known as Flakka.

The drugs dramatically altered his behaviour, and he became aggressive with a friend. He later left home with a knife from his kitchen, and neighbours called the police. He had discarded the knife by the time police arrived.

Image caption Mr Bayoh had lived in Scotland since he was 17

Mr Bayoh, who was originally from Sierra Leone but had lived in Scotland since he was 17, was restrained by six officers and lost consciousness. He died at hospital soon after.

Days after his death, the Scottish Police Federation (SPF) lawyer Peter Watson told the media that "a petite female police officer was subjected to a violent and unprovoked attack by a very large man who punched, kicked and stamped on her."

The new evidence obtained by BBC Disclosure casts doubt on this account.

What does CCTV show?

Image caption CCTV footage shows Mr Bayoh in the street before officers arrived at the scene

A leading authority on police restraint and use of force, Eric Baskind, of Liverpool John Moore University, analysed the documents, which included the first statements given by the officers involved.

The documents reveal that before Mr Bayoh's alleged stamping attack on the officer, three officers discharged their irritant spray into his face and a fourth drew her baton at him.

Mr Baskind said: "What strikes me from the evidence of the officers is that they approach the scene with the intention of using force.

"He's not running away, he's not, at that moment in time, creating a danger to anyone.

"They get there, they screech to a halt, they get out of the cars with irritant sprays and batons. That to me doesn't seem measured.

"That is not best practice. And all of those actions were very escalatory."

Image caption Later the images show Mr Bayoh on the ground being restrained by officers

The CCTV shows that Mr Bayoh hits the female officer, known as Officer D, knocking her to the ground. The officer had injuries consistent with being hit on the head.

Mr Baskind said this could have been prevented, if the officers had approached Mr Bayoh "in a different way, in a calming way, to try and find out what was wrong".

Police statements

The SPF claim about the stamping incident is based on the testimony of two officers, known in the statements as B and C.

Officer C said: "He stomped on her back with his foot with a great deal of force. He put his full bodyweight into the stomp and used his arms to gain leverage."

In her own statement, Officer D does not say she was stamped on. There's no mention of it in the statements of three civilian witnesses who saw the incident either.

The CCTV casts serious doubt on this claim. As soon as Officer D is knocked to the ground by Mr Bayoh, it looks as though the action immediately moves elsewhere, and Mr Bayoh is engaged by the other officers, and within five seconds, he is brought down.

Officer D appears to get up and walk away with another officer's help.

Image caption Eric Baskind, a leading authority on police restraint and use of force, has analysed the documents and studied the CCTV

Mr Baskind said: "The quality of the footage is not very good, but you can certainly make out what's going on, and I can see no evidence at all of two stamping attacks on the officer on the ground, let alone two very violent ones, that is described in the papers.

"It looks to me as though the officer's gone down, and pretty straight away Mr Bayoh is taken to the ground by others.

"There certainly seems to me to be a significant discrepancy between what I can see on the footage, and what I've read in the papers."

The BBC also obtained mobile phone footage of the incident, raising questions about how Mr Bayoh was restrained.

Officer B, who is 6ft 4in and weighed 25 stone, told investigators he had Mr Bayoh pinned to the ground for "a maximum of 30 seconds". Another said the restraint had been, "appropriate, text book stuff, in line with their training."

A civilian witness saw it differently. She told investigators officers were lying across Mr Bayoh for several minutes.

She said: "I heard him screaming. It sent chills through me. I heard the man shout to get the police off him. They never moved."

Image caption Deborah Coles, from the charity Inquest, said: "I think we cannot ignore the role that race may have played in this death."

Mr Bayoh suffered 23 separate injuries including a cracked rib, head wounds consistent with baton strikes, and petechial haemorrhages, or burst blood vessels in the eyes, which can be a sign of positional asphyxia, or suffocation.

Cause of death was noted as "sudden death in a man intoxicated…[drugs] whilst under restraint."

After the death, the Police Investigations and Review Commissioner (Pirc) launched an inquiry. Under advice from the SPF lawyer, the officers refused to provide statements to Pirc for 32 days.

BBC Disclosure has seen evidence which shows SPF advice to officers was to wait until the toxicology report was returned before giving statements.

Did race play a part?

The BBC has also seen evidence suggesting that Mr Bayoh's actions may have been distorted or exaggerated by police.

An internal police document written less than an hour after Bayoh's death said that police attended reports of a male with a "machete" in the street, and that the "male strikes one with machete".

None of the officers saw Mr Bayoh with a knife or machete, nor has there ever been any suggestion he struck one of them with a blade.

Police did not respond to questions as to how misinformation like this got into an official police document.

Deborah Coles, from the charity Inquest, which investigates deaths in custody, has been supporting the Bayoh family.

She told the programme: "The pattern that we've seen is that the state narrative is very often, when somebody dies after restraint, there is an attempt to demonise or speak ill of the person who's died…to try and deflect attention away from the actions of the police officers concerned [by] painting a picture of a dangerous man carrying a machete."

Image caption Mr Bayoh's sister Kadi Johnson says she has lost faith in the police and the justice system

She added: "I think we cannot ignore the role that race may have played in this death…and their immediate resort to the use of force.

"Racial stereotyping of black men as being…big, black, dangerous, informs the way in which they're treated, and the fact that they are over-policed."

The Bayoh family's lawyer Aamer Anwar, told the BBC that racism had been "the elephant in the room".

He said: "It always has been. It was the stories, it was the pictures, it was the stereotypical images of a large, black male crazed, acting erratically. It was all those things, the word "terrorist" being bandied about.

"Sheku Bayoh's family believes that race is central to this. The black community believes that race is central to this."

His sister Ms Johnson, told the BBC: "It has made me lose faith in the police and the justice system as a whole…I don't think he would have died if he hadn't met the police.

She added: "He wasn't himself, the way he was acting, but then no duty of care was given to him…because he was a black man. That's how we feel."

In 2015, the BBC revealed allegations that one of the officers involved in the restraint, PC Alan Paton, had a history of violence and racism.

Inappropriate to comment

Claire Baker, MSP for mid Scotland and Fife, said the allegations in the Disclosure programme were "shocking."

She added: "I recognise the police do a difficult job…but something went wrong, which raises questions about whether the police's response was proportionate.

"I think there should be a public inquiry."

The Scottish government said it was considering a public inquiry.

Police Scotland said it could not comment while the case remained open. A spokesman offered sympathy for the Bayoh family.

The Scottish Police Federation, which represents some of the officers involved in the restraint, said it would be inappropriate to comment until all legal processes were complete, but it added that the BBC sought to publish "fundamental inaccuracies" about the case.

Additional reporting by Sandeep Gill.

Disclosure: Dead in Police Custody will be broadcast at 20:30 on Monday and will be available afterwards on the BBC iplayer.