Hillsborough appeal for Leppings Lane Gate C witnesses
Detectives leading a criminal investigation into the Hillsborough disaster have released CCTV images of 19 men they want to speak to.
Ninety-six fans were killed as a result of the crush at the football ground in Sheffield in April 1989.
Images of potential witnesses at the stadium's Leppings Lane end have been released as part of Operation Resolve.
Senior investigating officer Neil Malkin stressed the men pictured "had done nothing wrong".
Det Ch Supt Malkin said the men seen near Exit Gate C when it opened at about 14:50 were in the "right place at the right time" and may be able to identify others.
"Together with evidence already gathered, it would mean we can provide a complete picture of events to the Crown Prosecution Service," he said.
"We just want to focus on them to try and conclude what happened. The potential evidence could help shape our understanding of what happened at Gate C."
In April an inquest jury concluded the 96 who died at Hillsborough were unlawfully killed.
It found a number of errors by South Yorkshire Police and South Yorkshire Ambulance Service, as well as stadium defects, contributed to the deaths.
Operation Resolve is one of two criminal investigations ordered following the publication of the Hillsborough Independent Panel's report in 2012.
A separate criminal investigation by the Independent Police Complaints Commission is examining police conduct.
Some relatives of those who died have expressed concerns over the new appeal for witnesses near Gate C.
Lou Brookes, who lost her brother Andrew at Hillsborough, told the Victoria Derbyshire programme earlier she was "absolutely disgusted".
She said: "I have serious concerns for their motives and objectives for pursuing this issue."
Lawyer Elkan Abrahamson, who is representing a number of Hillsborough families, said: "Operation Resolve in the course of the inquest came up with an absurd theory that Gate C was opened before [police match commander] David Duckenfield gave the order to open it.
"When we corrected this they then abandoned that theory and they seemed then to be pursuing another theory that even if it was opened after the order was given, it wasn't opened because of the order."
"If that is the theory that they are still pursuing I just can't see the point in it."
An Operation Resolve spokesperson said comments made by some families had been raised and considered."
They added: "Our job is to conduct a thorough and impartial investigation particularly around the opening of gate C.
"We are keen to identify and interview the 19 people in our witness appeal as we believe that they could hold vital information."
Operation Resolve has taken more than 1,200 statements from fans who approached from the Leppings Lane end on the day of the disaster.
A video reconstruction of the ground as it was in 1989 has been created to help jog people's memories.
Det Ch Supt Malkin said: "We are hoping with the context people will recognise themselves or friends and family. These people may recognise each other.
"We want to hear their experience of entering through Gate C, how they came to be there at that time, what they saw, what they heard."
The detective urged people to come forward and to inform police if any of the 19 have since died so they can be eliminated from the investigation.
A file is expected to be passed to the Crown Prosecution Service at the end of the year.