Xena, a five-year-old Belgian Malinois based in Sweden, has spent months being trained for a specialist crime-fighting role, as a police dog trained to sniff out sperm.
Swedish detectives say dogs can be trained to sniff out anything from bodies to bombs, but they have not heard of other forces using dogs in this way before. Senior officers are yet to decide if Xena can be used in active service.
Captain Lena Thor, of the canine unit of Vastra Gotaland County Police, Gothenburg, said Xena's training started after a request from the criminal investigation team.
"We thought about it for a while then decided to try out a dog we thought was suitable," she told the BBC News website. We have a lot of rapes which are outside, in parks, and sometimes it is hard for the victim to tell us exactly where it happened.
A dog's sense of smell is hundreds of times better than that of humans, and though Belgian Malinois were bred originally to herd and guard sheep, Police dogs also hunt for drugs, explosives and firearms
Xena is described as a typical police dog - "fond of looking for things and not afraid of anything" - is also trained to search out flammable liquids.