That person of interest is 27-year-old Joseph Dorsey, who was the last person seen with the deceased woman, identified as 47-year-old Christine Stewart.
Officials say Dorsey, Stewart's boyfriend, was last seen driving a 1994 Ford Explorer with California license plate number 6UDY773. The car is dark blue with a gray hood and front fender.
Dorsey is described as a white male, about 6 feet 1 inch tall with brown hair.
Authorities found Stewart's body at about 2 p.m. on Wednesday at the Best Western Plus on the 13800 block of Poway Road in Poway. Investigators believe Stewart was murdered elsewhere, and then taken to the motel.
Both Stewart and Dorsey were reported missing on Monday. They were last seen Saturday night in the Lake Elsinore area.
If you have any information about this case, you're urged to contact the sheriff's Central Homicide Unit at (951) 955-2777.
City News Service contributed to this report.