Prompted by an anonymous tip, presumably from the burglar, police found three videotapes of sexual abuse against children aged about 10.
The tapes had been placed beneath a brown car parked in the south-central city of Jaén, along with a note giving them the address of the suspect, police said in a statement.
"I have had the misfortune to have these tapes fall into my hands and feel obliged to submit them so you can do your work and put this … in jail for life," the anonymous note read.
The alleged aggressor was identified from the content of the videotapes and arrested after a search of his home and the indoor football club where he worked, police said.
Officers said they had so far traced four victims, including a 16-year-old boy who had been abused since he was 10.
The suspect had reported a burglary at his home nine days earlier, listing several appliances as stolen but making no mention of his missing video camera and tapes, police said.