Joshua Jacques, 29, has been jailed for life for murdering his girlfriend and three of her family members.
Jacques claimed he stabbed Samantha Drummonds and her family as a “sacrifice” after attacking them in their home in Bermondsey, south London, in April 2022, the Old Bailey heard.
He will serve a minimum term of 46 years for their murders.
The bodies of Ms Drummonds, 27, her mother Tanysha Ofori-Akuffo, 45, grandmother Dolet Hill, 64, and Ms Hill’s partner, Denton Burke, 58, were found after police were alerted to a disturbance by a neighbour.
The judge said Jacques had committed the “horrific catalogue of murders” after abusing skunk cannabis.
Mr Justice Bryan said they were carried out “in the most brutal of circumstances on three generations of the same family” after Jacques had increased his daily intake of the drug.
Jacques, who was fuelled by drugs and alcohol when the attacks took place, was found by armed police at the scene, lying naked in the upstairs bathroom in a praying position. He was screaming “Allah, take me!”, “Kill me now”, “Get rid of me”, and “God please forgive me”.
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At Lewisham Hospital, he later said: “I ain’t even in the wrong, I did them for sacrifice”.
He also warned: “I will do something stupid again”.
Jacques took 3g of skunk cannabis a day, the court heard, and had said he would continue to smoke the drug “even if it killed” him.
The judge said he was “well aware” of the impact the drug had on his mental health and warned: “It is a salutary lesson to all those who peddle the myth that cannabis is not a dangerous drug.
“It is, and its deleterious effect on mental health and its potential to cause psychosis is well established.”
In a victim impact statement, the daughter of Ms Hill and the sister of Ms Ofori-Akuffo said her mother had only just beaten cancer when she was murdered.
Tracey-Ann Henry said Ms Hill had her last radiotherapy session the day before she was stabbed.
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In his impact statement, the husband of Ms Ofori-Akuffo said he had “cried like a child” after learning of the attack.
Describing the horror of identifying his wife’s body, Danny Ofori-Akuffo said: “I remember wailing out in pain”.
“My heart had shattered into pieces.”
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Paul Raudnitz KC, mitigating for Jacques, read out an apology on behalf of his client at the sentencing hearing. It was the first time Jacques had expressed remorse for his actions.
“I would like to say to the family of the deceased, I am truly and sincerely sorry for all of the anguish, pain and heartache I have caused,” Jacques wrote.
He added: “I have discussed it with myself and I cannot believe that I am the cause of this monstrosity.”
Mr Raudnitz said the attack was not pre-meditated.
Jacques was found guilty of four counts of murder at the Old Bailey in December last year.
He had admitted manslaughter but denied murder on the grounds that he was mentally unwell at the time.