£50k reward offered for finding Parklife punch killer.
Robert Hart, 26, died after Parklife Festival assault.
Attacker remains unidentified despite £20k reward.
Renewed appeal for info on BBC's Crimewatch Live.
Victim's mom: "Robert loved music, should be alive."
Incident sparked over inflatable doll at festival.
Police seek man and woman involved in assault.
Suspect described as mixed race, mid-20s, 6ft tall.
£50k reward for information leading to conviction.
Detectives urge festival attendees to share images.
Dana Carvey Apologizes to Sharon Stone: SNL’s Controversial Sketch Revisited
Learn more