He killed mother-of-five Helle Christensen – his girlfriend at the time – by cutting her head off, eating parts of her body and then boasting about it on the internet.
His new girlfriend previously stabbed a single father to death and drunk his blood – posing in a picture online, before her arrest, with blood dripping from her lips, holding a power saw and a knife.
A caption underneath read: “I want to cut the throats of people on the subway.”
And so it is that Sweden’s most evil couple – a cannibal and a Satan-worshipping vampire – have applied to join in possibly the most unholy matrimony ever devised behind the bars of their secure psychiatric hospital.
Isakin Jonsson, 33, has asked human vampire Michelle Gustafsson, 23, if the fellow killer wanted to be his girlfriend on November 13 last year via internet messaging service MSN.
They decided to get engaged on December 9.
The couple are fellow inmates at the high-security Karsuddens psychiatric facility near Katrineholm, where they are expected to remain for the rest of their lives.
Both opted for indefinite psychiatric treatment to save them from automatic life sentences.
But experts believe they are both so sick they will die in captivity.
And as the usually liberal Sweden is horrified by their crimes, no politician in the future would risk an imploding career by ordering their release.
Yet the diabolical duo live in hope. Gustafsson posted on the internet this week: “We want to live together at some point, have dogs and pursue our hobbies: piercing and tattoos.” She made no mention of their other hobbies:
killing people and ritualistically consuming them.
Her cannibal fiancee added: “I love Michelle.
Have never met anyone like her. I want to live a non-criminal life.”
Justice authorities have not said whether their request to be wed will be granted.