Elsie Frost, 14, was attacked from behind and stabbed in the back and head as she walked through a railway tunnel just off a canal towpath in Wakefield, West Yorkshire, in October 1965.
Police renewed efforts to find her killer last year with refreshed publicity five decades on from her death, and received new information.
The suspect, who has been named in reports as Peter Pickering, was arrested in Berkshire but has now been bailed.
Senior investigating officer Detective Superintendent Nick Wallen, of West Yorkshire Police, said: “We have now bailed a man arrested yesterday, pending further inquiries. Our investigations into Elsie’s murder remain very much ongoing.”
A major inquiry was launched after Elsie’s body was found at the bottom of a flight of steps by a dog walker, and hundreds of people were interviewed but her killer has evaded justice ever since.
The renewed police inquiry was triggered by a BBC Radio 4 investigation into the case.
In the wake of the fresh police appeal, Elsie’s brother, Colin Frost, spoke out about her family’s pain, saying that their parents, Edith and Arthur, had died “with a huge amount of guilt”.
Mr Frost said Elsie had been like a mother to him, adding: “She was just a sweet, sweet person. She was lovely.”
In 1966, Ian Bernard Spencer, then aged 33, was charged with her murder but cleared on the orders of the judge who heard the case at trial.
Mr Frost told Radio 4’s World At One this week: “As a family we are very pleased. All we wanted was to be taken seriously.
“We were aware that mistakes were made in 1965, but we’ve been impressed with the commitment of West Yorkshire Police in the reinvestigation, the number of officers involved, the number of agencies involved.”