Their investigation hit the right note, however, when an Aberfeldy resident spotted an appeal online.
Jon Plunkett revealed the upright piano was being used as prop for a video being filmed in the area.
Musician Foy Vance, who has toured as a support act for singer-songwriter Ed Sheeran, was inspired by the local scenery and decided to make the most of it for his latest single.
Mr Plunkett said: “Foy had this idea about putting the piano into the river for the song. There were some really good shots and by the time filming was finished, we decided to come back the next day and move it.
“I then got a call from a friend telling me I was a wanted man. I suppose we should have left a note on the piano to say we were coming back.”
He has since contacted police to clear up the confusion.
For those interested in catching a glimpse of the piano, Vance’s new single Closed Hand, Full of Friends will be released next week.