Officers are trying to trace a former fairground worker in West Yorkshire.
Police want to speak to Michael Clark in connection with an ongoing enquiry.
He is believed to be from the Castleford or Airedale areas, and aged in his late 60s to early 70s, a spokesperson for West Yorkshire Police said.
The spokesperson said he also worked on fairgrounds in the 1960s.
Anyone with information is asked to call police on 101, quoting crime reference number 13170260407