LAS VEGAS (AP) — A defense lawyer says drug use may play a role in the murder case against a 47-year-old woman accused of killing three people last week at a Las Vegas home where they all lived.

Attorney Robert Langford said Thursday following a brief court appearance that Christine Rose Sanchez is disabled by a back injury and takes prescription medication. Langford declined to specify the drug.

Langford also represented Sanchez in a previous murder case that prosecutors dismissed last June. It stemmed from the September 2014 death of a woman in North Las Vegas.

Langford says Sanchez plans to plead not guilty to shooting 43-year-old Natasha Henry, 39-year-old Stanley Herring and 34-year-old Cordell Jones to death Dec. 22.

Police say the owner of the home heard gunshots and saw Sanchez with a gun before she left the house.