By Claire Harrison & Tim Hanlon Three teenagers have been jailed for manslaughter after killing a man out walking his dog following weeks of abuse. The trio – a boy and girl, both 16 from Nuneaton and a 15-year-old from Wilnecote, Staffordshire – who cannot be named for legal reasons have beenjailed following the death of John Hackett in Snow Hill Recreation Ground on April 25 last year. Mr Hackett was taken to hospital and after discharging himself, was later found dead by his mother – for whom he was her carer – the following morning at his home. At Warwick Crown Court today, Judge Justice A…