Detectives in Los Angeles searching for an actress who disappeared last month from her Hollywood apartment found a body they believe is hers on Tuesday nearly 400 miles north, buried in a Northern California wildlife area, the police said.

The woman, Adea Shabani, 25, had been missing since the afternoon of Feb. 23, when a security camera in her apartment building captured her taking luggage onto an elevator with her boyfriend. Her friends and family never heard from her again, prompting the police to start what became an expansive investigation that spread out from Los Angeles to the foothills of the Sierra Mountains to Colorado.

The search ended on Tuesday. Along a creek in the Spenceville Wildlife Area, detectives recovered a person’s remains in a shallow grave in a vast nature reserve in Nevada County, about 20 miles northeast of Sacramento. While the coroner’s office has yet to identify the body, the police believe the remains belong to Ms. Shabani, Capt. William P. Hayes of the Los Angeles Police Department said at a news conference on Tuesday afternoon.

Shortly after her friends officially reported her missing on Feb. 25, the police focused on her boyfriend, Christopher Spotz, who was seen leaving the apartment with her. According to the police, Mr. Spotz, 33, who was engaged to another woman, told detectives that on Feb. 23, they stopped for coffee in Hollywood and then headed north for his father’s home in a town outside Sacramento.