Disturbing messages sent between two lovers planning the murder of an innocent woman have been revealed in court as they were both jailed for life. Killer Gemma Watts laughed and giggled in court, winking at her co-accused Steven Sansom, whom she called her "evil twin". He was already a convicted murderer, released on licence when he met Watts and the pair began a depraved seven-month relationship where they exchanged messages about shoving his hand down her throat and making her vomit, watching pornography involving dogs, and a video of Sansom beating Watts with a wooden spoon.

The murderous pair admitted murdering Sarah Mayhew between March 7 and April 3, and perverting the course of justice by dismembering Ms Mayhew’s body, distributing the parts at “various locations” and cleaning up the scene. They had invited Sarah to come over for a party, before slitting her throat and later chopping up her body. A human bone belonging to Ms Mayhew had been discovered on the morning of April 2 last year by a dogwalker and their pup. Police were called to the scene, and arms, legs, and a head found nearby were confirmed to be Sarah's following DNA testing. Her limbless torso was discovered by contractors carrying out cleaning work in the River Wandle in Mitcham, on the afternoon of Tuesday, May 21.

Prosecutor Tom Little KC told the pair's sentencing hearing that among the many messages between the pair Watts had written a letter where she said Sansom should have no liability if she died during one of their sex games. There were also messages about them having sex covered in blood, and the two dying together if they were ever caught. Mr Little played out a voice note from Sansom that says: "Everyone looks like meat now, don't they. A play thing. Something to cut, something to bleed." Watts responded: "I wonder what they taste like, cooked flesh." Sansom replied: "People taste like pork, consistency, texture is the same.".

Tom Little KC who has prosecuted some of the country's most high profile cases, including the murder of Jo Cox MP, the kidnap, rape and murder of Sarah Everard, and the murder of Sir David Amess MP, read out other messages from Watts. One read: "Why do I walk round now looking at people different, little kids look different, babies all people I see them and picture how they would look begging for life, or cute little clothes torn and littles limbs covered in blood …. twisted and broken." Watts then said it makes her feel "horny, powerful hungry for it, different to everyone else". In another voice note played to the court, Sansom says: "I love how you are. I love how f**ked up we both are.".

Today, during sentencing Mrs Justice Cutts said: "Sarah Mayhew had a difficult life. But her greatest misfortune was to know the two of you." Her parents both gave victim impact statements. Her mum Angela said: "Since my daughter was murdered, I struggle to sleep most nights. She was a beautiful pretty girl who had lots of friends who were around from her childhood. Despite her issues she was still my daughter and I know she is up in heaven with the angels. It's a tragedy her two kids were 12 and 15 when their mum went like this.".

Her dad David told the two accused of murdering his child: "Firstly I would love to thank you both for at least having the decency to plead guilty to this crime. That said, whatever sentence you receive, it will never compare to the pain you have caused us. It's heartbreaking. I ask myself the same question all the time. That is: Why? Why did you have to kill her? I also feel for your families. You have destroyed their lives, but at least you will get the opportunity to see them again. We never will.".

Samson was sentenced to a whole life order meaning he will die in jail and Watts was sentenced to life with a minimum term of 29 years and 90 days behind bars. The judge told Sansom: "It's clear Sarah was murdered in that flat that night. Precisely what happened cannot be known... but [the messaging] leaves me in no doubt you lured Sarah to that flat for violent and depraved activity. Her fear and suffering must have been acute." Addressing Watt she added: "She was an innocent woman lured to that flat to die in order for you to act out your bloodthirsty and wicked fantasies.".

Sansom is facing his second life sentence, having been jailed in May 1999 after admitting the murder and robbery of a minicab driver on Christmas Eve the previous year, when he ordered a cab to take him home from East Croydon. The victim in that case, 59-year-old married father-of-two Terence Boyle, had crawled from his cab after Sansom attacked him and stole £25 to buy presents. Sansom, then 20, laughed afterwards and told a friend: “His kids are going to have to see him in hospital over Christmas.”.