Mendocino County Authorities Investigate “Serial Killer” Allegations
ALBION, CA — “On 03/14/2025, the Mendocino County Sheriff’s Office learned about social media posts where the subject alleged her father is a serial killer. The social media posts state the alleged serial killer is Jon Charles Trefil.
This situation was reported to the Mendocino County Sheriff’s Office in January of 2023 after Trefil’s daughter reported to other local and regional law enforcement of her suspicions that her father is a serial killer.
Based on the referrals from other law enforcement agencies, Mendocino County Sheriff’s Office Detectives spoke with an advocate of Trefil’s daughter, who also assisted in interviewing Trefil about his alleged crimes. Recordings, scanned journals, and other investigative materials were shared with the Sheriff’s Office who conducted investigations into the claims. Investigators met with Trefil’s daughter in February of 2023, who said her father spoke about murdering several people from the 1970s trough the 1990s. Trefil’s daughter also provided a lengthy written statement to Detectives, which was retained as evidence.
As Trefil, his daughter, and the advocate spent time together, Trefil’s daughter said her father spoke about these killings and the daughter began researching unsolved murders in Mendocino County. Trefil’s daughter suspected her father was responsible for a murder in the 1970s in Mendocino County, which she specifically questioned her father about. Per Trefil’s daughter, Trefil ultimately admitted to the unsolved murder in Mendocino County in the 1970s. Detectives also obtained pictures, copies of journal entries, and recordings from the meetings between Trefil, his daughter, and the advocate.
To further investigate the unsolved murder from the 1970s in Mendocino County, Detectives researched that case and compared the information provided by Trefil’s daughter to the facts of the case. Detectives learned there were numerous evidentiary items that were submitted for DNA analysis in 2006 to the Department of Justice, which resulted in an unknown male DNA source from the analyzed evidence. Detectives determined there were some consistencies in the information provided by Trefil’s daughter and the unsolved homicide case from the 1970s so they sought a warrant to obtain Trefil’s DNA for comparison to the evidentiary items sent for testing.
In May of 2023, the search warrant was authorized by a Judge in Mendocino County to obtain a DNA sample from Trefil for comparison to the DNA profile from the evidence items in the unsolved homicide from the 1970s. The DNA sample from Trefil was submitted to the California Department of Justice Bureau of Forensic Services and ultimately uploaded to the Combined DNA Index System (CODIS).
In 2023, the Mendocino County Sheriff’s Office received reports from the California Department of Justice regarding the comparison of Trefil’s DNA profile to the evidence in the unsolved murder case from the 1970s. Trefil’s DNA did not match the unknown male contributor DNA profile from the unsolved 1970s murder investigation. The Mendocino County Sheriff’s Office was also informed by DOJ that Trefil’s DNA profile was uploaded into CODIS for routine and regular comparisons to DNA profiles uploaded from unsolved cases. As of the publication of this press release, the Mendocino County Sheriff’s Office has never been informed of Trefil’s DNA profile being a match or potential match to any evidentiary items submitted to CODIS.
Information from Trefil’s daughter also alleged her father buried numerous people he murdered at a cabin in Comptche, CA. The Mendocino County Sheriff’s Office searched the property and cabin and were unable to locate any evidence to substantiate these claims or of possible human remains or burial sites on the property in Comptche.
The Mendocino County Sheriff’s Office is aware that Trefil’s daughter referenced other serial killers identified by her father, but these inferences were not substantiated by Detectives. The Sheriff’s Office has been unable to substantiate the claims of the other individuals alleged to be serial killers or their involvement with homicides in Mendocino County.
The Mendocino County Sheriff’s Office has examined the scanned copies of Trefil’s diaries and journals, but did not locate any expressed confessions to any murders.
Trefil’s daughter informed the Sheriff’s Office she submitted her DNA and Trefil’s DNA to genealogical / ancestry sites, but the Sheriff’s Office has never been informed of any investigative leads from these efforts or from other agencies investigating these claims.
The Mendocino County Sheriff’s Office has and will continue to investigate crimes associated with Trefil or allegations that he was a serial killer in Mendocino County. The Sheriff’s Office has not interviewed Trefil directly regarding these allegations due to his fragile medical state and information provided by his family that he will not cooperate with law enforcement. When legally justified and supported by probable cause, the Mendocino County Sheriff’s Office will continue to investigate this matter.
Anyone with information regarding this investigation is requested to contact the Mendocino County Sheriff’s Office at 707-463-4086 (option 1). Information can also be provided anonymously by calling the non-emergency tip line at 707-234-2100.”
