"I don't know why, I can't get them out of my mind because what's happened to Jimmy is the worst thing possible, but we've got such wonderful memories.
"They haven't got wonderful memories for their son. All they can think about is the evil he's done. My prayers are with the family, that's all I can say. I can't, I don't feel anger."
Jimmy had six brothers, Danny, 30, Billy, 28, Tommy, 26, Bobby, 24, Harry, 18 and George, eight, and two sisters, Joanne, 35, and 21-year-old Samantha.
Mr Mizen, 56, said: "He loved his family, his family loved him. Jimmy was able to express that love as well.
"You could give Jimmy a hug, no problem at all. Jimmy would give me a kiss when I dropped him off at school. You don't see many teenagers do that."
"An innate decency ran through Jimmy's body. He was a decent, fine young fella, protective of other people, protective of maybe the weak."
Jimmy is the 13th teenager to have been fatally attacked in London since the start of the year.
On Sunday, London's new mayor, Boris Johnson, joined thousands of Christians praying for an end to violence in the wake of Jimmy's death and that of Lyle Tulloch, in Borough, south London, a week ago.
Speaking at the Global Day of Prayer, held at Millwall Football Club, Mr Johnson said: "In the last few days we have seen the deaths of Lyle Tulloch and Jimmy Mizen and I'm sure their parents will be in our prayers."
He also said: "There are too many parents across London today who have lost their young children or young teenagers in the last year to gun crime and knife crime... together we can do something and together we must do something and together we will do something."
LOCATIONS OF TEENAGE KILLINGS IN 2008
(1) 1 January: Henry Bolombi, 17, stabbed, Edmonton, north London
(2) 5 January: Faridon Alizada, 18, stabbed, Erith, south-east London
(3) 21 January: Boduka Mudianga, 18, stabbed, Edmonton, north London
(4) 26 January: Fuad Buraleh, 19, beaten, West Ealing
(5) 19 February: Sunday Essiet, 15, stabbed, Woolwich, south-east London
(6) 23 February: Tung Le, 17, stabbed, Westminster, central London
(7) 29 February: Ofiyke Nmezu, 16, beaten, Enfield, north London
(8) 13 March: Michael Alexander Jones, 18, stabbed, Edmonton, north London
(9) 14 March: Nicholas Clarke, 19, shot, Brixton, south London
(10) 27 March: Devoe Roach, 17, stabbed, Stoke Newington, north London
(11) 27 March: Amro Elbadawi, 14, stabbed, Queen's Park, west London
(12) 3 May: Lyle Tulloch, 15, stabbed, Borough, south London
(13) 10 May: Jimmy Mizen, 16, Lee, south-east London
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