Police have appealed to fairgoers who filmed the stabbing of the son of Big Fat Gypsy Weddings star Paddy Doherty to come forward.
David Doherty, 26, of Salford, was attacked at last month's Appleby Horse Fair in Cumbria when he received lacerations to his lower back.
Cumbria Constabulary said a large group of people filmed the incident in the Market Field area of the fair on their mobile phones and cameras.
Mr Doherty was taken to Cumberland Infirmary in Carlisle following the attack at about 12.35pm on Sunday June 5 but was released the same day.
His father Paddy has been thrown into the media spotlight following his appearance in the hit Channel 4 documentary series.
Detective Sergeant Peter Goulston said: "Since the incident took place, a thorough investigation has been ongoing and we have been working to identify witnesses.
"It has been brought to our attention that there were a lot of people who appeared to be filming the incident with handheld cameras or on their mobile phones - so they may have important footage that can assist our investigation. If this was you and you have footage that you think can help us, please get in touch.
"I'd also like to make a direct appeal to members of the media who were filming throughout this year's event. If you captured any footage of the incident at the time or have since been sent any amateur footage of the incident, please contact police as your footage may be the important piece of evidence we need."
Anyone who thinks they can help police with their investigations should contact Det Sgt Goulston on 0845 33 00 247.
A 29-year-old man from Toll Bar, Doncaster, and a 26-year-old man from Barnsley have already been charged with assault causing grievous bodily harm. Three other men from South Yorkshire remain on police bail.