The Disappearance of Pem Michelle Yates-Briggs, late 1970s

Very little is definitively known about Pem Michelle Yates-Briggs's disappearance. She was born on March 31, 1963 in Norfolk, VA. Her mother's birth name is Barbara Cecile Briggs, though she seems to have changed her name to Bo Monique Bradley some time after Pem's disappearance. According to Pem's half-sister, the man listed as Pem's father on her birth certificate was J Yates; however, this is supposedly not Pem's actual birth father.

Photo from NamUs.

At some point after Pem's birth, she and her mother moved to Oregon c.1971, and Barbara remarried to a man named Denman Wehrli Sr. Pem has two half-siblings from this marriage, born in 1972 and 1974, respectively: Dewana Wehrli (sister) and Denman E Wehrli Jr. (brother). According to Dewana, she (Dewana) was the product of rape by an unknown person during Barbara's marriage to Denman Sr. Pem may have used the surnames Yates, Briggs, Yates-Briggs, or Wehrli.

The family seems to have lived in White Salmon, Washington state from about 1973-1974 before moving back to Oregon. Pem attended middle school in Post, OR, and attended high school in Hood River, OR; however, according to one Ancestry post, in 1978 (though unsure if for the full year) Pem attended Sam Barlow HS in Gresham, OR. She would have graduated high school in spring 1981.

According to Pem's half-sister Dewana, their mother Barbara had five children, including two she gave up for adoption, to at least four different men. Dewana has stated that Barbara was a drug user and migrant worker, and was physically abusive toward her children. Barbara reportedly "neither condoned nor condemned" the sexual abuse of Pem at the hands of her (Pem's) step-father, Denman Wehrli Sr. By the time Dewana was five years old, Barbara and Denman Sr had gotten a divorce, and Barbara started dating a man named Wayne Allen Schutt, who reportedly also molested Pem up until the time she disappeared.

Dewana believes that Wayne Schutt "has everything to do with Pem's disappearance," and was alive up to at least April 2022. Dewana also believes that Pem may have been buried in Klickitat County, WA. For Dewana's full account, see the WebSleuths and Crimewatchers threads linked below.

The date of Pem's disappearance is uncertain and inconsistent: for example, CA DOJ gives her date of last contact as January 1, 1979, which is likely a placeholder date. I have used the date on NamUs and Charley Project — June 1, 1979 — for the sake of consistency. However, all sites and sources — except for CA DOJ — mention the lack of clarity.

The earliest date mentioned is 1977, by Pem's mother. However, due to the photo of her in the 1978 Sam Barlow High School yearbook, it is known that Pem had to have attended high school for at least part of the 1977-1978 school year. This means that, if she did in fact go missing in 1977, she had to have done so sometime after the school year started in August or September 1977.

However, it is generally agreed upon that Pem was 15-16 years old when she went missing, and/or that she disappeared in 1978 or 1979. Pem turned 15 on March 31, 1978, and (would have) turned 16 on March 31, 1979. According to Pem's half-sister Dewana, "she may have disappeared even later between 31-Mar-1979 to 30-Mar-1980"; Pem would be 16 at the time.

In total, Pem may have gone missing anytime between August 1977 and March 1980.

Pem was last seen alive by her family when she voluntarily left their home in Oregon City, Clackamas County, OR — with her mother's permission — to search for her father in California. Pem was last heard from a few days after she left. On that day, Pem's mother Barbara received a phone call from a police department in California, asking if Pem had permission to be across state lines / to cross the state line into CA. Barbara confirmed that Pem had her permission. That was the last time she was heard from.

Barbara was moving to Goldendale, WA at the time, and reportedly had no address to give her daughter. Barbara and Dewana — Pem's half-sister — have indicated that they believe she may still be alive and looking for her family.

Photo from NamUs.

Dewana first posted about Pem on WebSleuths in 2017, and it seems as though she has been looking for Pem for a while now. In January 2024 Dewana stated that she did not know how to create a NamUs page, and that she was uncertain how to file a missing persons report from another state. Pem allegedly was not reported missing at the time of her disappearance. Dewana has stated that up until her death, their mother Barbara would offer very little information about Pem and would reportedly lie to Dewana.

Pem was finally reported missing on March 15, 2024, and her NamUs and Charley Project cases were subsequently created.

Pem is a white female with blonde, shoulder-length hair and brown eyes. At the time of her disappearance she was 5'3 - 5'6 and 110-125 lbs. CA DOJ specifically states that Pem was 5'7 and 120 lbs. She has a crooked front tooth and a cleft in her chin.

Pem's DNA seems to be available from her half-brother Denny. Her dental x-rays are not available for comparison. Her mother Barbara has passed away as of 2021. Pem is classified as Endangered Missing, and the Clackamas County Sheriff's Office is investigating her case. She has one rule-out on NamUs, Valencia Jane Doe 1980.

Anyone with information regarding Pem is asked to please contact Detective James White of the Clackamas County Sheriff's Office at (503) 785-5000. The agency case number is 24-005120.

Pem's NamUs case, which was created on March 26, 2024, is #MP118850, and was last modified on November 24, 2024. Her Charley Project profile was last updated April 30, 2024. Her MPIA case number is 271; her MPIA case profile was created on April 2, 2024, and was last updated on March 27, 2025. Pem's profile was added to the Doe Network on April 17, 2025; this write-up was originally written prior to the creation of her DN profile, however everything seems to be in line with the information I have gathered.