A California man says he was under the influence of cough syrup and marijuana when he allegedly killed his 84-year-old grandmother.

Matthew Levine, 35, turned himself in about a month after the incident. He had originally reported Dorothy Autrey missing, according to the San Luis Obispo Tribune.

A report from the Sheriff’s Department says Levine smoked marijuana and ingested three bottles of Robitussin DM at Audrey’s home on Feb. 20.

Levin then disrobed, according to the report, and went downstairs to the kitchen where Autrey chastised him for being naked and urged him to change his lifestyle. Levin claimed he turned around to confront her and accidentally struck her in the chest, sending her crashing into the counter and onto the floor, the report says.

Thinking she was dead, investigators said Levin then dumped her body off a remote ocean cliff, the San Luis Obispo Tribune reported.

Pharmacist Dana Nelson told The Tribune large amounts of cough syrup can create hallucinations, euphoria, muscle relaxation and lack of inhibition, as well trigger feelings of anger.

Levin is due in court Sept. 11 for a pretrial conference, the paper reported.

Click here to read the full article from the San Luis Obispo Tribune.