Lynne Diane Siewert

Status:

Open

Jurisdiction:

Siskiyou County Sheriffs Department (CA)

Missing From:

Seiad Valley, CA

Summary:

Lynne Diane Siewert, 54, also known as Lynne Smethurst, was last seen on March 23, 2023 at the Seiad Valley Post Office in western Siskiyou County. An unconfirmed sighting placed her in Happy Camp on April 20. At the end of April the black Chevrolet truck she had been driving was found abandoned, stuck on China Grade Road off Highway 96. Deputies and her family have searched the area without finding her. She remains missing.

Vital Statistics

Circumstances of Disappearance:

Lynne Diane Siewert, also known as Lynne Diane Smethurst, was 54 years old and living in the Happy Camp area of western Siskiyou County, along the Klamath River. According to the Siskiyou County Sheriff's Office, she was last seen on Thursday, March 23, 2023, at the Seiad Valley Post Office. A second, unconfirmed sighting placed her in Happy Camp on April 20, 2023. She has not been heard from since. At the end of April 2023, the black Chevrolet truck she had been driving was found abandoned, stuck on China Grade Road, a Forest Service road off Highway 96. She was reported missing to the sheriff's office in May 2023. On May 15, 2023, deputies searched the truck and the surrounding area but found no sign of her or of where she might have gone, and the vehicle produced no new leads. Deputy Aaron Jacobsen said investigators had not ruled out any possibility and were following every lead, but were keeping their leads private. The sheriff's office said on May 24 and 25 that there was limited information it could release to the public. Early news coverage, based on the sheriff's May 2023 appeals, described her as last seen driving her truck in the Happy Camp area around April 20; the sheriff's Unsolved Siskiyou page now lists the March 23 post office sighting as the last confirmed one and the April 20 sighting as unconfirmed. In late May and early June 2023, her sister, Selina Smethurst, and her daughter, Alyssa Siewert, who live in Southern California, spent five days in Happy Camp interviewing residents and searching the area where the truck was found. They said they found fabric and blonde hair near the truck and turned everything over to deputies, and they publicly criticized the sheriff's office for giving them few answers. They also said a sheriff's search with four cadaver dogs had not alerted on anything. A deputy told KOBI-TV there was no update on the case but acknowledged the family's frustration. The family said the area where the truck was found is so remote that they do not believe she would have driven there on her own and fear foul play may be involved. Ms. Siewert has four children and two grandchildren. She is listed in NamUs and the California Department of Justice missing persons database, and the Siskiyou County Sheriff's Office carries her case on its Unsolved Siskiyou list. As of April 2026 she had not been found and the case remains open.

Additional Details:

Anyone with information is asked to call the Siskiyou County Sheriff's Office 24-hour dispatch center at (530) 841-2900.

Case Last Updated:

Oct 23, 2026