Erin Schweikert, 18, was found wrapped in a plastic bag, decomposing inside a storage container in January, in the basement of the home where Maddison Leidy lived.
Schweikert, who went missing in October, was last seen along Front Street after telling her family she was meeting with someone.
Immediately after the discovery, 26-year-old Leidy was charged with abuse of corpse and tampering with evidence, among other charges.
But detectives continued their investigation, digging through cell phone records and social media posts, and eventually, law enforcement sources say, gleaning enough digital evidence to charge her with murder.
Sources say Schweikert had both heroin and fentanyl in her system when she died.
Leidy remains behind bars at Riverside Correctional Facility.