A waiter was today found guilty of helping his schoolboy cousin take revenge on his ex-girlfriend by murdering her in a house fire.
Shihabouddin Choudhury, 21, of Coventry Road, Nottingham, was recruited by 14-year-old Akmol Miah to help torch the home of Maleha Masud.
Maleha and her 21-year-old sister Nabiha died as as result of the blaze which took place in June last year in Tooting, south London.
Miah, now 15, of Broadway Avenue, Croydon, was convicted of their murders yesterday at the Old Bailey by a unanimous verdict, as well as the attempted murders of the girls' brothers Zain and Junaid, and mother Rubina.
Choudhury was today found guilty of the same counts by 11-1 majority.
Both face life sentences when they are sentenced on July 9.
A third defendant, 19-year-old waiter Rasal Khan, of Earl Howe Street, Leicester, was cleared of all the charges.
The court heard that the fire was started by petrol poured through the Masud family's letterbox in revenge after Miah was dumped by Maleha.
A day before he searched on Google for "how to burn someone's house down".
Zain, a 24-year-old banker, A-level student Junaid, 18, and mother Rubina, 55, survived the blaze but said they faced a "life sentence" of grief after the deaths of Maleha, the "baby of the family", and Nabiha, who was engaged to be married.
Mrs Masud wept as she said: "I miss them a lot."
Zain said: "It is hard to contemplate why anyone would do such a thing."
Maleha died three days after the fire and Nabiha a month later.
Junaid was rescued from the flames by firefighters while Zain and Mrs Masud leapt to safety from a first floor window,
Miah - who can be named today after reporting restrictions were lifted - wept as he was found guilty of the girls' murders yesterday.
The court heard he had previously threatened Maleha that if she did not continue their relationship he would "do something to her and her family".
Jonathan Laidlaw, QC, prosecuting, said that Maleha had been in a "relationship of sorts" with the boy, who was 14 at the time, but it was not a serious one.
"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," he added.
"Why he should arrive at the extraordinary decision to burn down their house is really impossible to understand. It was obviously not the reaction of an ordinary and normal 14-year-old, however hurt he might feel about losing a girlfriend."
After the fire, police said they were faced with a "real whodunit" but found out about Maleha's relationship with the boy after visits to schools and an appeal to the community by local Labour MP Sadiq Khan.
When the boy was arrested for murder he said: "I can't believe she is dead."
A search of the computer in his bedroom found he had looked up how to burn someone's house down on Google and that pictures of the burnt and boarded-up property had been downloaded from the news websites and stored as the screensaver.
The boy, who looked several years older than his 15 years, claimed in court he loved Maleha and he did not start the fire - although he said he had been jealous of her talking to other boys.
Judge Christopher Moss ordered psychiatric and psychological reports on Miah after expressing his concern at "the apparent confidence with which he appeared to give evidence".
"This is a young man who seems to me to be mature beyond his years," he said.