A school caretaker was jailed for life today for killing his lover after lacing her omelette with sleeping pills.
Stephen Singer then battered Dina Sharpe's head and trapped her in her blazing bedroom, where she died.
He was ordered to serve a minimum of 23 years after the judge at the Old Bailey said he had committed the murder to find a "chilling" solution to a complex love triangle.
Singer, 37, was also jailed concurrently for 20 years for the attempted murder of a toddler in the flat in Southwark, south London, and six years for arson.
Brave neighbours tried in vain to save school cleaner Miss Sharpe, 39, after she desperately tried to get help by calling from a window of the fourth-floor flat, were praised by the judge.
After breaking down her door, they were only able to rescue a 17-month-old boy from the inferno.
The court was told that Singer had been having a three-year relationship with Miss Sharpe while living with another woman.
Things came to a head last summer when the woman found out and threw him out.
At the same time, Miss Sharpe found out that Singer was trying to get back with his long-term partner.
On Sunday August 2, Singer bought sleeping tablets and lighter fuel before going to Miss Sharpe's home in Charlton House.
After he calmly left and rode off on his motorcycle, Miss Sharpe's cries were heard and she was seen calling for help from a window.
Judge Stephen Kramer said Singer had argued with Miss Sharpe and punched her three times in the face and head, causing the brain damage from which she died.
He had planned the murder, grinding up sleeping pills earlier in the evening and trying to sedate Miss Sharpe by adding them to an omelette he had cooked for her, and to her wine.
Singer had set fire to the flat to cover up his "calculating and callous" crime.
The judge told him: "You are a controlling person who was prepared chillingly to use aggression and deceit to take control of a complex triangle of your own making."
Andrew Munday QC, prosecuting, said the little boy, who cannot be identified for legal reasons, survived but had 75% burns and was still undergoing extensive plastic surgery.
He said Miss Sharpe died from brain damage due to injuries to her head and face, not from the fire.
After her death, her blood was found to contain sleeping pills. Items from the flat were re-examined and the same drug was found in wine and in half an omelette.
"Not only did he spike the omelette, but also the wine," said Mr Munday.
"He made an omelette but left his half. There was a plan by this defendant to cause her a fatal overdose or at least to incapacitate her."
Miss Sharpe's cousin, Deborah Judge, told the court: "To us, Dina died a hero. We will never understand why Stephen Singer didn't just walk away."
Outside court, Detective Chief Inspector Carl Mehta said: "This is an absolutely horrific case and the level of callousness and brutality used by Singer to plan and execute the murder is just unimaginable."Reuse content