It was no mystery to Jerry Strickland and Melissa K. Munday when police showed up at their door in Moses Lake, Wash. Hours earlier they had been watching television as the show "Unsolved Mysteries" mentioned them in connection with the unsolved robbery and slaying of a gas station worker near Pontiac, Mich. Police got about 15 calls from area residents after the program aired, and Officer John Mays and Sgt. Dennis Duke arrived to find the couple waiting for them, Mays said. Warrants charge Strickland, 26, with homicide, armed robbery and fraud, and Munday, 17, was wanted for investigation of a homicide in the 9-month-old slaying. They were held in the Grant County Jail, awaiting extradition. Mays said the couple had been in the Moses Lake area since June, he working at K mart and she at a card shop. The crime victim, gas station courier Elmer DeBoer, was kidnaped and shot twice in the back of the head, and more than $10,000 was taken in the robbery, said Waterford Township, Mich., Sgt. Don Bailey. Munday had been assistant manager at the gas station and Strickland worked at another station, he said.