Mayor Sue Murray conducted the brief ceremony at City Hall.
Lee, the son of Danny Lee, Greencastle, and Kerri Duncan, Indianapolis, served as a reserve officer for GPD for four years prior to his recent selection as a full-time officer by the Greencastle Board of Public Works and Safety, acting on a recommendation from the GPD Board of Captains.
The 2006 South Putnam High School graduate officially began his duties Monday and will become a member of the City Police night shift starting Friday. GPD officers currently serve in 12-hour shifts.
Officer Lee said he has always been interested in police work and his career path began in earnest after he took the Vocational Law Enforcement class at the Area 30 Career Center.
Lee is one of 15 officers serving under Greencastle Chief Tom Sutherlin.
Technically, he succeeds Chris Helmer, who left GPD to join the Speedway Department in 2011. GPD has been running one officer short ever since.
Lee is expected to attend the Indiana Law Enforcement Academy at Plainfield in April.
Chief Sutherlin, Assistant Chief Brian Hopkins, Dets. Randy Seipel and Michael Collins and a number of other GPD officers attended the swearing-in ceremony in support of Lee.