Gwent Police has issued these two CCTV pictures in an appeal for information following a serious assault.
A 32-year-old man was found on a pathway near Addison Way, in Graig-Y-Rhacca, with serious head injuries on Friday June 25.
Police now believe the man was attacked in the area of Caerphilly Castle in Caerphilly town centre, sometime between 10pm Thursday and 1am Friday, and not Graig-Y-Rhacca as originally thought,
He remains in the University of Wales Hospital in a critical but stable condition.
Two local men aged 20 and 21 were arrested in connection with the incident and two further men aged 21 and 24 have also been arrested.
All four men have been released on police bail pending further enquiries.
Police have released CCTV stills of two men they believe may have witnessed the incident and could hold vital information that could assist the police enquiry.
If anyone has information about the incident they are asked to contact Gwent Police on 01633 838111 or Crimestoppers on 0800 555111.