The father of murdered schoolgirl Becky Watts has described the shock of seeing his 16-year-old daughter's mutilated body.

Darren Galsworthy spoke about viewing Becky’s body in the morgue while speaking to the ITV documentary The Murder Of Becky Watts: Police Tapes.

He said: “When we saw her in the morgue, that's when it really hit us. I mean, they did their best to cover up where he cut her up and things like that. But I could still see where he’d decapitated her.”

“No parent should have to see that,” Mr Galsworthy added.

Becky was murdered and dismembered by her stepbrother, Nathan Matthews, with help from girlfriend Shauna Hoare in February 2015 in one of the most brutal cases in Bristol’s history.

The documentary, which will air on 9 November on ITV1, will feature exclusive interviews with Becky’s relatives and the officers who worked on the case.

Matthews was jailed for 33 years for murder and his girlfriend sentenced to 17 years for manslaughter after the jury found the pair had killed her in a sexually motivated kidnap plot.

“The image I have, in my nightmares, is him holding her down on the floor, and [Hoare’s hand] over her mouth... They did it together, they planned it together, I don't know what they expected to gain from it. ‘Cause there was nothing in it for them. So, it was all pointless”, Mr Galsworthy told presenter Susanne Reid.

Becky went missing on 19 February 2015 from her family home in Bristol and her dismembered body was found two weeks later hidden in a number of suitcases in a garden shed.

One aspect of the investigation the show will reveal is that the police chose not to tell Matthews his blood had been found in Becky’s room, instead only hinting at the discovery, in order to put pressure on him.

In pictures: Becky Watts murder trial Show all 16 1 /16 In pictures: Becky Watts murder trial In pictures: Becky Watts murder trial Views of Rebecca Watts' bedroom at her home at 18 Crown Hill, St George, Bristol, where the prosecution claim she was suffocated on the day she vanished on 19 February 2015 PA In pictures: Becky Watts murder trial The bath - where Becky's body is said to have been dismembered - is clean and tidy In pictures: Becky Watts murder trial The bathroom is littered with clothes, a cooker, microwave and bags In pictures: Becky Watts murder trial Nathan Matthews being interviewed by police after Becky Watts' body parts had been found In pictures: Becky Watts murder trial Shauna Hoare being interviewed by police following the murder of Becky Watts In pictures: Becky Watts murder trial One of the suitcases used in the murder of Becky Watts, shown to the jury at Bristol Crown Court In pictures: Becky Watts murder trial One of the suitcases used in the murder of Becky Watts In pictures: Becky Watts murder trial One of the suitcases used in the murder of Becky Watts, shown to the jury at Bristol Crown Court. In pictures: Becky Watts murder trial One of the suitcases used in the killing of Becky Watts In pictures: Becky Watts murder trial The lounge of 14 Cotton Mill Lane, Barton Hill, the home of her stepbrother Nathan Matthews, 28, and his girlfriend Shauna Hoare, 21 In pictures: Becky Watts murder trial The bathroom at 14 Cotton Mill Lane, Barton Hill, the home of Nathan Matthews and his girlfriend Shauna Hoare In pictures: Becky Watts murder trial 14 Cotton Mill Lane, Barton Hill, the home of Nathan Matthews, 28, and his girlfriend Shauna Hoare, 21 In pictures: Becky Watts murder trial CCTV still issued by Avon and Somerset Police of Nathan Matthews and his girlfriend Shauna Hoare entering the 99p store in Bedminster on 22 February 2015 In pictures: Becky Watts murder trial Nathan Matthews is seen buying a circular power saw at B&Q In pictures: Becky Watts murder trial A photo from 2012 believed to show Nathan Matthews, 28, and his partner Shauna Phillips, 21 In pictures: Becky Watts murder trial Murdered teenager Becky Watts' uncle, Sam Galsworthy and aunt Sarah Broom arrives at Bristol Crown Court on October 5, 2015

“Without giving that to them on a plate, if you like, it leaves them having to think about it, and puts them under more pressure,” explains Detective Constable Marie Stephen.

Police found receipts from B&Q which included a circular saw, goggles and face mask which led them to believe Matthews had dismembered the body.

Matthews eventually confessed in a prepared statement.

However, Hoare's involvement was only discovered after deleted text messages were found between the pair which showed how they planned to kidnap and kill young girls.