A central Pennsylvania woman accused of having killed her elderly grandmother with drug-laced chili almost four years ago is now charged with first-degree murder.

Forty-year-old Shelby Lyn Adams of York appeared Tuesday in York County Court to waive formal arraignment on a criminal homicide charge, but prosecutors amended the charge to first-degree murder. She is also charged with forgery, theft by deception and receiving stolen property.

Prosecutors allege that the defendant stole checks from 90-year-old Ada Adams and forged and cashed them, then killed the victim with morphine-laced chili in April 2008 to cover up the thefts. Authorities say she was working in a hospital emergency room and had access to leftover morphine.

Chief Public Defender Bruce Blocher said his client maintains her innocence.