Detectives investigating the death of a man four days after an alleged assault have released images of a man they believe can help them. Colm Marcus Boston, 37, from Heath, died four days after an incident on Pentyrch Street in Cathays on the evening of Monday, December 22, 2025.
An inquest opening previously heard he was found with multiple injuries following an alleged street attack. A CT scan upon his admission to hospital showed a traumatic head injury.
Police appeal for witness
Police are now appealing for a man seen on a CCTV recording to come forward, as they believe he could have important information. They stressed that the man has "not done anything wrong".
The CCTV footage shows Mr Boston crossing the road outside Tesco on Cathays Terrace at the same time - at around 5.50pm - as the unknown witness. This is the last sighting of Colm on CCTV before police were called at around 6.15pm.
Arrests and family tribute
A police statement read: "It is important to stress that the unknown man has not done anything wrong but may have important information. Four men have been arrested as part of the investigation. One is released under investigation. The others remain on police bail. Mr Boston’s family continue to be supported by family liaison officers."
Following his death, Mr Boston's family said: "Colm was a father, a son, a brother, a cousin, and a deeply loved friend to many across Cardiff and beyond. Colm lived a complex life, with its highs and lows, but he loved the people in his life fiercely and mattered greatly to so many. His loss has left a profound impact on all who knew him. We would like to express our heartfelt appreciation to the nurses and doctors at University Hospital of Wales, who were absolutely amazing in their care, professionalism, and unwavering support of Colm and our family. Their kindness and dedication will never be forgotten."
Information and footage can be submitted online. Alternatively, please contact South Wales Police quoting 2500404113.
