Officers investigating the death of Fahad Nur are trying to identify three potential witnesses and are appealing for them to get in touch.
18-year-old Fahad Mohamed Nur died after being stabbed near Cathays Railway Station on June 2.
CCTV enquiries in and around Cathays have put three men, seen in the below video clip, in the vicinity of the lane around the time of the incident.
Officers believe they could potentially have information which may assist their investigation – but stressed they are not under suspicion of any offence.
“Despite extensive enquiries these men have not yet been identified. I must stress they are not under suspicion of any offence nor are they linked in any way to Fahad’s death”, Detective Mark O’Shea of South Wales Police said.
Three people have been charged with murder and detectives are not looking for anyone else in connection with Fahad’s death.
The individuals captured, or anybody who thinks they can identify them, are urged to contact South Wales Police on 101.