Police are urging passengers who witnessed an attack on a bus in West Yorkshire to come forward.
Officers want to hear from anyone who was on the 203 single decker bus between noon and 1pm on Saturday, February 11.
An elderly man who was travelling on the bus was assaulted by another male passenger as the bus neared the retail park on Leeds Road, Huddersfield.
The victim was left with injuries to his right cheek and nose.
As well as speaking to any witnesses, police want to trace a white male in connection with the incident.
He was sitting behind the victim and wearing a dark coloured hooded top with the hood up.
PC Vicky Wilby, of Huddersfield Police, said: "We have been carrying out extensive enquiries but so far have been unable to trace this individual.
"We believe there were people on the bus who may have witnessed this incident and I would appeal to them to come forward with information."
Anyone with any information is asked to contact the police on 101, quoting crime reference 13170067727.