Paul Mallin killed Karen Read and John Down in “brutal circumstances” at Fernways sheltered housing unit in Cecil Road, Ilford, in September 2015.
It has now been revealed that Mallin died of natural causes aged 59 whilst on compassionate release from HMP High Down.
Mallin, who had been diagnosed with cancer in October 2022, died at a hospice in February last year.
Mallin had been sentenced to 19 years in prison in April 2016 after he pleaded guilty to two counts of manslaughter on the basis of diminished responsibility.
The Old Bailey had heard that Mallin had become angry his fiancée Miss Read, 53, had chosen his 86-year-old neighbour over him in February 2015.
Mr Down and Miss Read had subsequently got engaged.
The court also heard he had searched for “poison” more than 300 times on his phone, including “poison that doesn’t show up in an autopsy” and “Ricin Breaking Bad” in reference to the TV show.
On September 5, at around 10pm, Mallin tried to force his way into Mr Down’s flat with a knife and a meat cleaver.
Mr Down was trying to push the door so the defendant could not enter, but Mallin slashed around the door with the knife and got in.
He stabbed the great-grandfather “multiple times”.
The court heard disabled Miss Read must have been able to see this brutal death from her armchair – unable to move – before Mallin turned the knife on her.
Judge Richard Marks KC, who sentenced Mallin, said: “They were completely defenceless and highly vulnerable.
“They suffered terrible injuries and met their deaths in the worst possible circumstances.”
