Sports clubs and schools in Bath and across Avon and Somerset are being warned to make sure that no cash or valuables are left in unlocked changing rooms.
It follows a series of thefts in the past two months at cricket matches in which mobile phones, laptops, MP3 players and cash worth thousands of pounds have been stolen.
There have been six thefts reported so far: at the University of Bath, the Sulis Club, King Edward’s School changing rooms in North Road, on Lansdown Road and in Bathampton, and one at Monkton Combe School cricket pavilion.
Bath police believe one man is responsible for those, and for an identical series of thefts during rugby matches in the area last September.
They are appealing for anyone who knows, or who has information about, 60-year-old Anthony Tye who they want to talk to about the thefts.
He is wanted for two similar offences at the Clifton College and Bristol Grammar sports grounds in the Failand area of Bristol in April, and for similar thefts in Preston in Lancashire and Edgbaston in the West Midlands.
PC Margaret Wood of Bath’s Priority Crime Team said: “Anthony Tye is really confident and casual, blends in with the crowd and when he is spoken to always has a good level of local knowledge about the teams and the area.
“Although he has that good local knowledge he is not a local man. We believe he may be staying in a guest house, and he appears to move around on buses and on foot.”
Tye is described as white, 6ft tall, with greying brown hair. He dresses casually and usually carries a black rucksack.

This CCTV image released by police shows Tye in Monkton Combe
PC Wood said: “We’d like to hear from anyone who may have seen a man fitting his description, or perhaps spoken to him, at any sports grounds or matches recently.
“Our strong advice is that no valuables or money should ever be left in changing rooms. Always put them in a bag and give it to a nominated and responsible person for safe keeping.”
Anyone with information should call Bath police on 101 quoting crime reference number 43595/14.