A MONSTER mum and her boyfriend who laughed as they tortured her schoolboy son to death have been jailed for life.
Sebastian Kalinowski, 15, died of an infection caused by "untreated complications of multiple rib fractures" following weeks of "cruel assaults and abuse".
The boy was beaten with a bed slat, whipped with an extension cable and stabbed with a needle before he died on August 13 last year.
Sebastian's "supposed caregivers" - his mum Agnieszka Kalinowska, 35, and her long-term partner Andrzej Latoszewski, 38 - were both found guilty of his murder.
And today, Kalinowska and Latoszewski were jailed for life with a minimum term of 39 years at Leeds Crown Court.
The jury previously heard how the pair laughed as they tortured the boy during their campaign of evil abuse.
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In a chilling victim impact statement, Sebastian's devastated dad branded Kalinowska and Latoszewski "ruthless monsters without an ounce of human feeling".
He asked his son's mother: "What kind of mother are you?"
Dad Jacek Kalinowski told the court: "I am the father of Sebastian Kalinowski. There is not a crime crueller than murder, especially when it involves a child.
"You turned every day in his life into a nightmare and committed monstrosities that are truly mindboggling.
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"I will never comprehend how much hatred it takes to do such thing. The question is why? Why did you hate him to such a degree you let that psychopath treat him like that?
"How could you let your child be harmed? You took everything from him - his dignity and life.
"You hit him with an extension cable, a wooden slat. Who gave you the right to raise your hand against your child?"
Speaking to Latoszewski he said: "You made my son a punchbag for yourself. You were merciless and destroyed him every single day.
"You were truly a brutal tyrant. Why do you hate him so much?"
Sentencing Kalinowska and Latoszewski, Mrs Justice Lambert told them: "You, Latoszewski, are a bully.
"Like all bullies, you sought to intimidate and frighten Sebastian, who was weaker than you.
"In Sebastian you found an easy prey.
"There were times when viewing the footage I was sure you had lost awareness of the fact that you were hitting a human being and not a punching bag.
"As for you, Kalinowska, the explanation is simple, you just didn't care about Sebastian. You were only interested in yourself."
A jury previously heard how 15-year-old Sebastian had been in the UK for less than a year after moving from Poland to live with his mother and her boyfriend.
It was not long after moving here that the youngster started being subjected to a campaign of "torture".
After the couple were arrested in connection with Sebastian's death, police seized CCTV cameras from their house in Huddersfield, West Yorkshire, which prosecutors said had been installed partly to "monitor and exert control over Sebastian remotely".
But prosecutor Jason Pitter KC previously told the court: "In a twist, it is that system that has recorded the abuse he had to endure."
Jurors heard that on the morning of Sebastian's final day, he went through "the routine of being assaulted by both defendants".
Mr Pitter said CCTV showed Latoszewski taking Sebastian out of the bedroom at 8.25am, before carrying him back around 15 minutes later, "naked, clearly wet and unconscious".
He said: "Whilst some limited efforts were made by Latoszewski to perform CPR, the reality is it may have been too late as Sebastian showed no sign of life once he was brought back into the bedroom.
"At 9.24am, Latoszewski appeared to be trying to pour water into Sebastian's mouth before then blowing into it.
"Was that the beginnings of an attempt to give the impression that Sebastian had drowned by trying to force water into his airways?"
When emergency services were eventually called to the house, Sebastian had been unconscious for two and a half hours, the Crown Prosecution Service said.
He was taken to hospital where he was pronounced dead.
[They] were the two people Sebastian should have been able to trust the most in the world.
Daniel Lee
Latoszewski suggested variously that Sebastian had drowned in the bath, had fallen from a tree, and had been in a fight.
Videos showed numerous incidents in which Sebastian was repeatedly punched, kicked and stamped on. In one video, he was shown being whipped with a cable.
The teenager was shown being force fed and, in one incident, had a slipper shoved into his mouth with such force that he bled.
Senior Crown prosecutor Daniel Lee said: "Agniewska Kalinowska and Andresz Latoszewski were the two people Sebastian should have been able to trust the most in the world but instead of loving, protecting and caring for Sebastian, they subjected him to an utterly horrific and prolonged campaign of extreme physical and mental abuse.
"In short, they tortured him. After suffering many months of mental and physical torment, Sebastian died of the multiple injuries he sustained at their hands.
"Both defendants lied and offered cowardly and implausible explanations for the extent of Sebastian's injuries, and attempted to pass it off as 'appropriate discipline'.
"It is impossible to contemplate the agony and fear this young boy experienced, inflicted in his own home, by his supposed caregivers."
"The defendants are now facing very many years in prison. Our thoughts remain with Sebastian's other relatives and we sincerely hope the successful outcome of this case will bring them some comfort."
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Kalinowska and Latoszewski initially denied murdering Sebastian.
But, Latoszewski admitted manslaughter on the second day of the trial, while both defendants pleaded guilty to child cruelty a day later.