A 42-year-old Pleasanton man is suspected of killing the woman he was living with and leaving her body on the Alameda shoreline in July, authorities said Thursday.

The remains of the woman, identified as 27-year-old Rachel Elizabeth Imani Buckner, were found July 20 by someone walking on a trail near the Bay Farm Island Bridge, Alameda Police Chief Nishant Joshi said Thursday.

"It's a very disturbing case," Joshi said. Buckner's body was dismembered and wrapped in plastic, according to police. Buckner's family has been notified and is devastated, the chief said.

Joseph C. Roberts, 42, was arrested Wednesday in connection with the death, by the U.S. Marshals Service and police from Pleasanton and Alameda.

The victim was identified by her DNA, and evidence led detectives to Roberts.

Detectives have not determined a motive in the death, and it hasn't been determined when she was killed, Joshi said.

Roberts is due to be arraigned on Friday morning in Alameda County Superior Court.

Anyone with information that might assist the investigation is asked to call Alameda police at 510-337-8402.