FORT COLLINS - A former police officer who conducted surveillance on Tim Masters in 1988 believed that an elaborate operation - which included planting a fake story in the local paper - was a ridiculous undertaking aimed at the wrong person.

But Troy Krenning, who was a patrol officer at the time, volunteered for the assignment because it meant overtime pay and maybe the chance to help crack a horrible crime - the Feb. 11, 1987, murder of Peggy Hettrick.

"Words can't describe how absurd I thought that was at the time," Krenning said Tuesday afternoon in Larimer County District Court, during a hearing on motions filed by Masters' attorneys.

Masters, who was convicted in 1999 of killing Hettrick, is fighting for a new trial on the grounds that police and prosecutors hid evidence favorable to him.

Hettrick was stabbed in the back and sexually mutilated. Her body was found in a field behind the mobile home where Masters, then a 15-year-old high school student, was living.

He was interrogated at length, and as the first anniversary of Hettrick's murder approached, police had not made an arrest.

Investigators considered it significant that Masters' mother, Margaret, had gone into the hospital Feb. 11, 1983 - exactly four years before Hettrick was killed - and died the next day.

According to documents produced in court this week, they thought it was likely that Masters would act out around the first anniversary of Hettrick's murder and, perhaps, even commit a "similar" crime.

So they hatched a plan that included around-the-clock surveillance and a planted story in the local paper.

All of it, Krenning said, was aimed at trying to "gather incriminating information through the use and means of psyching this kid out and pushing him toward the edge psychologically."

But a police officer who followed him on the anniversary of the killing later wrote that Masters "never seemed to be very stressed at any time."