The stepbrother of Becky Watts treated her body with "a lack of compassion and humanity" but that does not make him guilty of murder, his barrister told a jury.
Nathan Matthews, 28, allegedly suffocated his 16-year-old stepsister in a sexually motivated kidnap plot with girlfriend Shauna Hoare, 21, on February 19.
Becky's body was moved from her home in Crown Hill, Bristol, and dismembered in the couple's bath in Cotton Mill Lane, Bristol, with a circular saw.
Her remains, packed into suitcases and a blue plastic storage box, were discovered in a garden shed 80 metres away by police on March 3.
A jury of 10 women and one man heard the closing speech of Matthews's case in Becky's murder trial, following 21 days of evidence.
Adam Vaitilingam QC, for Matthews, asked the jury to consider the evidence in the case instead of their emotions towards his client.
"A man who has shown himself to be capable of killing a 16-year-old and then treating her body with such a lack of compassion and humanity," he said.
"I do not ask for sympathy for Nathan Matthews. He deserves none.
"I ask that you approach his case in the same fair way you would approach any defendant charged with any crime.
"His right to a fair trial from an independent jury hasn't disappeared because of what he has done."
Mr Vaitilingam said Matthews went to Becky's home on February 19 with the plan to kidnap his stepsister to teach her a lesson.
But he accidentally killed her after trying to make her unconscious during a struggle to put her inside a red suitcase.
"I am sure you will feel nothing but contempt and loathing for Nathan Matthews, you will feel nothing but sympathy and pity for Becky and her family," Mr Vaitilingam said.
"You promised to try this case on the evidence, not on emotion and all I can ask of you is that you keep that promise."
Mr Vaitilingam told the jury Matthews admitted he plotted to kidnap Becky but denied he had done so with Hoare, his partner of six years.
That "badly conceived, bone headed, extreme and frankly absurd" kidnap plan resulted in Becky's death, the barrister said.
The former TA soldier was not motivated by a sexual attraction to Becky but rather her behaviour towards his mother, Anjie Galsworthy, he insisted.
"There is no evidence to suggest that he had a sexual interest in Becky," Mr Vaitilingam said.
"Nothing anyone noticed, nothing he said, nothing he put in a text or on Facebook in an unguarded moment."
In a police interview, Becky's father Darren Galsworthy said she was "was rude, abusive and disrespectful to Anjie" and Matthews did not like it.
Jurors previously heard how Becky's body was dismembered into eight parts with a £80 Mac Allister circular saw bought by Matthews at B&Q on February 20.
The body parts were moved into a garden shed in Barton Court in the early hours of February 24 by Matthews and two men.
Matthews, of Hazelbury Drive, Warmley, South Gloucestershire, denies murder and conspiracy to kidnap.
He admits killing Becky, perverting the course of justice, preventing the burial of a corpse and possessing a prohibited weapon.
Hoare, of Cotton Mill Lane, Bristol, denies murder, conspiracy to kidnap, perverting the course of justice, preventing burial of a corpse and possessing a prohibited weapon.
Karl Demetrius, 30, and his partner Jaydene Parsons, 23, the occupants of the Barton Court property, admit assisting an offender.
Donovan Demetrius, of Marsh Lane, Bristol, and James Ireland, 23, of Richmond Villas, Avonmouth, deny the charge.
Mr Vaitilingam told the jury: "What Nathan Matthews did to Becky's body afterwards will haunt all of us.
"It is grim evidence and it will stay with us for some time. It is not the actions of a rational man.
"He was hardly rational in that first interview with the police - that bizarre account and a rant about being a metrosexual and a Neanderthal.
"You have heard a lot about the way that Nathan Matthews's mind works and perhaps when he takes a decision about something - disposing of Becky's body to protect Becky's family from the consequences of the discovery - he does it.
"A sort of extreme logic which is true, as well, in his planned kidnap."
Mr Vaitilingam questioned whether his client had the "small voice of calm" most people have to protect them from doing something dangerous or extreme.
He said his client had a "black and white way of looking at the world" and could get upset or lash out if things were not going as he expected.
Matthews had no previous convictions before the start of this trial, he added.
"He is criticised for not showing sorrow, for not looking at the family when he was giving his evidence," Mr Vaitilingam said.
"You might say that he was hanging his head in shame for the terrible things he has done, in front of his own mother, in front of the man at whose wedding he was best man.
"Did he ever really intend to kill Becky and take her away from those two people? Did he mean to do it?"
Andrew Langdon QC, for Hoare, told the jury the case featured "the ghastly subject of the brutal killing and dismembering of a 16-year-old girl".
"Let's consider the Galsworthy and the Watts family and friends because their suffering and anguish is probably unimaginable for any of us," he said.
"Any mother, father, brother of a girl whose life is cruelly ended and whose body is desecrated suffers and continues to suffer whatever anyone does or says, whatever your verdicts - forever."
He said his client had a troubled upbringing, met Matthews as a young teenager while at school and lost contact with friends and family.
"Never mind who is responsible for that isolation, the fact is that unless Nathan allowed it she had very little contact with anyone else," Mr Langdon said.
Hoare was able to stand up for herself occasionally and consented to threesomes with Matthews and a female friend, he added.
"She was able to sent highly inappropriate texts to excite or to please Nathan," he said. "To appeal to his toilet humour as he inadequately termed it.
"Those text exchanges are shameful and she lied about them when confronted with them.
"Sex fiend Shauna Hoare? Her sexuality has moved centre stage in this trial. It is the motive advanced, the reason given for why she was involved in the kidnap plot."
The jury was read extracts of a police interview in which Hoare described her sex life with Matthews.
"It's not exactly Lady Macbeth is it?" Mr Langdon asked.
Mr Langdon said his client was provided with a council house because of her background and lived there with Matthews.
"She had to deal with a man who was not straight forward and was also moody and who would, when angry, assault her," he added.
"Not all victims of abuse are easy to sympathise with. It doesn't mean they are not being abused."
He said Hoare had low self esteem, was ashamed of her home and did not have any independence.
"The council gives her material things, a house, but the council can't give the love that turns a house into a proud home," Mr Langdon said.
"Her life and her house is filled both literally and metaphorically by Nathan Matthews - filled with his junk and his issues."