A park keeper and big fan of the CSI series of forensic criminal investigation TV dramas helped solve a murder in southern Spain when she bagged up vital evidence overlooked by police.

Carmen Moreno, who has been sweeping leaves and collecting rubbish in the María Luisa park in Seville for 28 years, went to clean up the mess the police left behind after a woman’s body was found in the park.

At the scene she noticed some bloodsoaked tissues and, following the procedures she had seen on TV, bagged them up separately so as not to contaminate the evidence.

“Behind the bench where she was found there was a pile of bloody tissues and panty liners,” she said. “Normally I carry gloves but I didn’t have any with me. As I’m a big fan of CSI I used a bag to pick them up so as not to contaminate them and I put them in another, small white bag which I tied with a knot.

“I then put this in a larger bag. It surprised me that the police hadn’t picked them up as there were also bloodstains on the bench.”

Police were called to the park on 23 February following the death of the 31-year-old woman, which they initially treated as suicide. No crime scene investigation was carried out.

Moreno said she found that puzzling, given the amount of blood at the scene. The woman, apparently depressed, had swallowed a number of tranquilisers. She was then approached by a man who raped her so brutally that she died of internal injuries. Later forensic tests showed the victim had not died of an overdose.

When Moreno’s shift ended she went to the beach with her family. “At half past two my boss called to ask if I knew where I’d put the rubbish I’d collected,” she said. “I told them exactly where it was and the police found it right away.”

The police matched the DNA Moreno found with that of a 46-year-old man who has a record of violence.

The prosecutor praised Moreno, saying that without the forensic evidence the case would have been difficult to prove.