A father was jailed for at least 26 years today for killing a man for asking if his crying daughter was all right.
Matthew Quesada, 26, over-reacted when Alan Smith, 63, approached the child, and took it as criticism of his parenting, the Old Bailey heard.
He went home and stabbed kindly Mr Smith five times in a "frenzied and silent" attack after tracing him to a local cafe.
Quesada, of Leyton, east London, was found guilty of murder and sentenced to life.
Judge Peter Rook told him: "You are a very dangerous young man. This was a truly grave crime.
"Your reaction was wholly unexpected and out of proportion. You over-reacted and took this as a slight on your parenting."
Quesada's partner, Maria Brigitte, 26, was found guilty of assisting an offender and given a nine month jail sentence suspended for two years and 200 hours unpaid work.
The court heard that Mr Smith was stabbed in front of his partner and daughter in revenge for asking if everything was all right with the little girl.
Mr Smith was in the BB Cafe in Leyton, east London, on March 26 last year when he asked Quesada about the crying child.
Quesada replied: "What's it to do with you? Go away. What's it f****** got to do with you?"
Mr Smith was "eager to avoid confrontation", and so went with his partner, daughter and son-in-law to the nearby Roma Cafe.
Meanwhile, Quesada took his daughter home to his partner Maria Brigitte, and came back with a knife that he used to wordlessly attack Mr Smith.
The next day he was found in a car with his mother Victoria Passley-Quesada, 54, having cut his hair. He had his passport with him and details of flights to Brazil.
Roger Smart, prosecuting, said the horrific murder had devastated Mr Smith's family.
His daughter Estelle Jennings felt guilt about his death and wished she had not gone to the cafe to celebrate her birthday.
His son Daniel Smith said in a statement: "He was the most important person in my life. My dad was like a guardian angel. I really miss him."
Daniel's brother Alex said their father was their "best friend". He added: "You could never meet a more loyal, generous and honest, amazing man."
Patrick Upward, QC, for Quesada, said the killer had been abused as a child and over-reacted when his daughter was approached by Mr Smith.
Acting Detective Chief Inspector Steve Meechan said outside court: "Alan Smith was a well-meaning man who simply wanted to inquire about a distressed child.
"He paid for his concerns with his life. Not happy with verbally abusing Mr Smith, Quesada went on to carry out a frenzied and unprovoked attack on a defenceless man."