A police officer testified Wednesday about an undercover operation to get a man to admit to killing a Saskatoon woman who disappeared in 2004.

Douglas Hales is charged with first-degree murder in the death of Daleen Bosse.

The lead officer, whose identity cannot be published due to a court order, described how his unit set up a "Mr. Big" sting to convince Hales he was being recruited into a national crime syndicate.

The officer told court the sting was capped off at a meeting between Hales and a fictional crime boss at the Radisson Hotel in August 2008.

The officer said it was at this meeting that Hales admitted to the murder and told them the location of Bosse's body.

When Bosse was last seen on May 18, 2004, the 25-year-old mother was beginning her fourth year as a student at the University of Saskatchewan where she was studying to become a teacher like her parents.