Human skeletal remains were unearthed beneath a dry-cleaning business in San Francisco’s Lower Pacific Heights neighborhood, authorities said Monday. Investigators are poring over missing-person reports and cold-case homicides to see if any fit the circumstances, police said. The county coroner’s office will try to analyze any DNA obtained from the remains. The skull and bones were found Friday afternoon when a contractor came to fix a plumbing issue at Perfect Cleaners on the 1900 block of Fillmore Street, a neighborhood filled with trendy, upscale shops and restaurants. “It’s a mystery,” said Officer Albie Esparza, a police spokesman.