A woman was bitten by a dog which was attacking her own in a park in Chesterfield.
The victim was walking through Holmebrook Valley Park with her two dogs when the incident happened.
Another dog, thought to be a red Staffordshire bull terrier which was not on a lead, then ran up to her animals and started to attack one of them.
The victim tried to force the dogs apart and was bitten on the hand in the process.
She suffered minor injuries and her dog was not seriously hurt in the incident, which happened at about 9.15am on December 7.
She reported that the attacking dog belonged to an elderly man who was also walking a white Staffordshire bull terrier, which was on a lead.
The man was white, about 5ft 8in, of medium build, in his late 50s or early 60s and was wearing a dark grey flat cap and long black winter coat.
He spoke with what was described as a Mediterranean accent, possibly Italian or Spanish.
Police want to speak to the man and would like to hear from anyone who knows who he is.
Witnesses or anyone with information should call PC Julian Matthews on 101, quoting reference 16000405484, or Crimestoppers on 0800 555 111.