A boy who took revenge after being jilted by starting a house fire which killed his ex-girlfriend and her sister has been convicted of their murders.
Maleha, 15, and Nabiha Masud, 21, died at the family home in Lessingham Avenue, Tooting, south London.
Their mother and two brothers were also injured in the fire last June, the Old Bailey was told.
The boy, aged 15, was also found guilty of three counts of attempted murder.
Rasal Khan, 19, of Earl Howe Street, Leicester, who was accused of helping the boy, has been found not guilty of attempted murder.
The jury is still considering verdicts in relation to two murder charges Mr Khan faces.
It is also considering verdicts in relation to Shihabouddin Choudhury, 21, of Coventry Road, Nottingham, who is also charged with murder and attempted murder.
During the trial the court heard how the boy, who cannot be named because of his age, had searched on Google for "how to burn someone's house down" the day before the fire.
The boy, who was 14 at the time of the murders, had been in a "relationship of sorts" with Maleha, the jury was told.
But after they split she complained that the teenager was blackmailing her and claimed he would tell her mother about their relationship.
Prosecutor Jonathan Laidlaw QC said: "The two of them broke up and it was then that (the boy) threatened Maleha that if she did not continue in the relationship he would do something to her and her family.
"Why he should arrive at the extraordinary decision to burn down their house is really impossible to understand."
Burned house screensaver
The fire was started by petrol being poured through the letterbox of the Masud family home and set alight while they slept.
The court heard that a search of the boy's home found that he had set pictures of the burnt and boarded-up property as his screensaver.
The sisters' mother Rubina, 55, and brothers Zain, 24, and Junaid, 18, all managed to escape.
Mrs Masud had shouted to her children to get out after being woken by the fire and eventually jumped from a window.
Zain also jumped but Junaid and his sisters remained inside. Neighbours could hear cries for help but were unable to mount a rescue due to the heat.
Maleha was discovered curled up at the bottom of her bunk bed. Her life support was withdrawn three days later.
Nabiha was transferred to a specialist unit in Chelmsford but died on July 25.
The court heard they were a high-achieving family with Zain having worked for Lehman Brothers and brother Junaid set to have a career in medicine or engineering.