Overview

• Full name: Teresa Lynn McKinley (née Wismer)
• Age at disappearance: 27
• Date last seen: September 16, 1979
• Last known location: Vacaville, Solano County, California
• Reported destination: Peña Adobe Park, Vacaville
• Case classification: Endangered missing person
• Current status: Unsolved; investigation reopened in 2024
• Investigating agency: Vacaville Police Department
• Police case number: 794613
• NamUs reference: MP18859
• Physical description: White female, 5 feet 3 inches tall, approximately 110 pounds, brown hair and green eyes
• Clothing when last seen: Yellow top, brown pants, carrying a white shoulder purse
• Distinguishing circumstances: Teresa disappeared after leaving home for an apparent visit to a local park. Her vehicle was recovered 16 days later near Lake Berryessa, but she was not found.

The California Department of Justice continues to list Teresa as missing. Her disappearance has not been officially established as a homicide.

Detailed Case Breakdown

Teresa Lynn McKinley: The Unsolved 1979 Disappearance of a Young Mother in Vacaville, California

On September 16, 1979, 27-year-old Teresa Lynn McKinley left her home in Vacaville, California, reportedly intending to spend some quiet time reading at a nearby park. She never returned. More than two weeks later, her green Volkswagen was discovered abandoned near Lake Berryessa, approximately an hour from where she had been living.

For decades, Teresa’s disappearance remained largely unknown outside her family. Her two young daughters grew up without answers about what happened to their mother. In 2024, however, investigators revisited the case, and a January 2025 news investigation brought renewed public attention to her disappearance.

Nearly half a century later, the central mystery remains: What happened to Teresa McKinley after she left home that September afternoon?

Case Summary

• Full name: Teresa Lynn McKinley (née Wismer)
• Age at disappearance: 27
• Date last seen: September 16, 1979
• Last known location: Vacaville, Solano County, California
• Reported destination: Peña Adobe Park, Vacaville
• Case classification: Endangered missing person
• Current status: Unsolved; investigation reopened in 2024
• Investigating agency: Vacaville Police Department
• Police case number: 794613
• NamUs reference: MP18859
• Physical description: White female, 5 feet 3 inches tall, approximately 110 pounds, brown hair and green eyes
• Clothing when last seen: Yellow top, brown pants, carrying a white shoulder purse
• Distinguishing circumstances: Teresa disappeared after leaving home for an apparent visit to a local park. Her vehicle was recovered 16 days later near Lake Berryessa, but she was not found.

The California Department of Justice continues to list Teresa as missing. Her disappearance has not been officially established as a homicide.

Sources: California Department of Justice; The Charley Project; SFGATE, January 20, 2025.

Teresa McKinley’s Life Before Her Disappearance

Teresa Lynn Wismer was born on August 17, 1952, in Los Angeles, California. According to a January 20, 2025, investigation published by SFGATE journalist Katie Dowd, Teresa grew up as a popular, creative young woman who was selected as a homecoming queen during her freshman year of high school.

Her life changed when she became pregnant at 16. She left high school and married her teenage boyfriend, Michael McKinley. The couple eventually had two daughters and relocated to Vacaville, where Michael worked repairing telephone equipment for Pacific Bell.

The move placed Teresa away from the familiar surroundings of Southern California and closer to her husband’s relatives.

Her daughter Heather Gonzalez recalled a mother who was artistic, attentive and deeply involved in raising her children. Teresa enjoyed painting, playing guitar, sewing clothing and styling her daughters’ hair.

Although family life presented challenges, Teresa was also planning for her future. She had recently completed her GED and hoped to establish a career as a hairstylist.

These ambitions are significant because her family has consistently questioned the idea that Teresa deliberately abandoned her children or voluntarily disappeared.

In interviews with SFGATE, Heather acknowledged that her parents’ relationship had experienced tension. However, those recollections do not establish that domestic conflict caused Teresa’s disappearance, and no publicly verified evidence identifies her husband as responsible for a crime.

Source: SFGATE investigation.

September 16, 1979: Teresa Disappears

On Sunday, September 16, 1979, Teresa left the family residence on Spindrift Way in Vacaville.

According to the account later provided to investigators, she intended to visit Peña Adobe Park, a recreational area near the city, where she planned to read a book.

The weather was hot that day, but her proposed outing appeared ordinary. There was no publicly documented indication that she intended to leave the region permanently.

When Teresa failed to return home after several hours, her husband contacted the Vacaville Police Department.

Detective Ron Head became involved in the initial investigation.

The circumstances surrounding Teresa’s final confirmed movements remain uncertain. Publicly available reporting does not establish that an independent witness saw her arrive at Peña Adobe Park, nor does it document precisely what happened after she left home.

The distinction matters: Peña Adobe Park was her reported destination, not a confirmed location where she was independently observed.

No verified subsequent contact with Teresa has been publicly reported.

Sources: The Charley Project; SFGATE.

October 2, 1979: Her Volkswagen Is Found Near Lake Berryessa

The most significant physical discovery occurred 16 days after Teresa disappeared.

On October 2, 1979, a Napa County sheriff’s deputy located her green 1979 Volkswagen Dasher abandoned along a road near Lake Berryessa in Napa County, California.

The vehicle bore California license plate 584XLH.

Investigators observed that one of the vehicle’s windows was broken. However, contemporary information summarized in later reporting did not identify obvious evidence of a violent crime inside the car.

According to SFGATE, the Volkswagen was not processed for fingerprints before being returned to Teresa’s family.

This decision potentially eliminated an opportunity to identify individuals who had handled or occupied the vehicle. However, there is no publicly verified evidence establishing whether useful fingerprints would have been recovered.

The location of the vehicle raised further questions.

Heather Gonzalez later explained that, to her knowledge, her mother had no meaningful connection to the Lake Berryessa area. She could not understand why Teresa would have traveled there when her reported plan was to visit a park near home.

The abandoned car remains a central element of the mystery, but its discovery does not establish who drove it to Lake Berryessa or whether Teresa was present when it arrived.

Source: SFGATE vehicle investigation.

Investigation History and Available Evidence

The original investigation

The initial police investigation considered Teresa’s emotional well-being in the weeks before her disappearance.

Approximately one month earlier, she had experienced a medication overdose described in reporting as a suicide attempt.

Investigators considered whether her disappearance might have been connected to suicide.

However, Teresa’s family disputed that interpretation. Relatives told SFGATE that Teresa had subsequently described the overdose as a mistake. They also pointed to her parenting, future career plans and personal correspondence as reasons they did not believe she intended to end her life.

These family observations are important, but they cannot independently establish Teresa’s state of mind or determine what happened to her.

Detective Kaley Sullivan, who later reviewed the investigation, told SFGATE that the prevailing theory in the original case file had been suicide. She acknowledged that this interpretation might have influenced the investigative response.

The publicly available record does not establish that a comprehensive search of every potentially relevant location occurred in 1979.

The loss of the original investigator

An unusual event affected the case’s investigative history.

In January 1981, Detective Ron Head fatally shot his wife, Janice Head, in an incident he described as an accidental shooting after mistaking her for an intruder.

According to SFGATE’s historical reporting, he was subsequently convicted on involuntary manslaughter and firearms charges, sentenced to four years in prison, and removed from the Vacaville Police Department.

This event occurred approximately 15 months after Teresa’s vehicle was recovered.

Heather Gonzalez later expressed concern that the detective’s departure contributed to the lack of progress in her mother’s case.

There is no publicly verified evidence linking Head’s crime to Teresa’s disappearance. His involvement is relevant because he was an investigator in the original case, not because he has been established as a suspect.

What physical and forensic evidence is publicly documented?

The publicly reported evidence is limited.

The strongest documented physical lead is Teresa’s recovered Volkswagen, including its location and broken window. The California Department of Justice also confirms that dental X-rays are available for identification comparisons.

The public record reviewed does not establish that investigators recovered a usable DNA profile, identifiable fingerprints, a weapon, or other forensic material directly demonstrating a crime.

Nor has a publicly confirmed forensic match to unidentified remains been reported.

Source: California missing-person record; SFGATE investigation.

Theories and Unresolved Questions

Several possible explanations have been discussed in connection with Teresa’s disappearance. None has been publicly established as fact.

Possibility of suicide

The original investigation reportedly gave considerable weight to Teresa’s earlier overdose.

However, no confirmed recovery of her remains or other conclusive evidence has established suicide as her cause of death.

Her family’s belief that she was not suicidal at the time must also be distinguished from a medical or investigative finding.

Possibility of an accident

An accidental death remains one possible explanation.

Lake Berryessa and its surrounding terrain present environments where a person could potentially become lost or suffer an accident.

Nevertheless, no verified evidence establishes that Teresa entered the lake, walked into surrounding wilderness, or experienced an accident.

The recovery of her car near the lake is not sufficient to establish that she died there.

Possibility of foul play

Teresa’s family has expressed concern that another person may have been involved.

The unexplained relocation of her vehicle, its broken window, and her failure to contact her children have contributed to those concerns.

However, the broken window was not publicly identified as proof of an assault, and investigators have not publicly established that a homicide occurred.

No officially named homicide suspect, criminal charge, or verified motive was identified in the reviewed case reporting.

Possibility of voluntary disappearance

Investigators historically considered whether Teresa might have left voluntarily.

Her daughter strongly rejects that possibility, citing Teresa’s close relationship with her children and her plans for the future.

There has been no publicly confirmed sighting, communication, or other evidence establishing that Teresa intentionally began a new life.

The fundamental unanswered questions concern Teresa’s actual destination, who last saw her, who drove the Volkswagen to Lake Berryessa, why its window was broken, and whether any unidentified remains might ultimately be connected to her disappearance.

Latest Investigative Developments: 2024–2026

The cold case is reopened in 2024

One of the most significant developments in Teresa McKinley’s case occurred in 2024, when the Vacaville Police Department reopened the investigation.

Detective Kaley Sullivan reviewed the historical case and began reassessing the circumstances surrounding Teresa’s disappearance.

According to SFGATE’s January 2025 reporting, investigators interviewed Teresa’s surviving family members, including her two daughters and her husband.

These interviews represented an important renewed effort to gather information and reconsider assumptions from the original investigation.

Detective Sullivan acknowledged that missing-person investigations in the late 1970s were handled differently than they are today. She also recognized that the original theory of suicide might have influenced how the investigation proceeded.

Renewed attention to unidentified remains

The reopened investigation also raised the possibility that Teresa’s remains could have been recovered elsewhere decades ago without being identified.

Detective Sullivan discussed the possibility that unidentified remains held by forensic laboratories could eventually provide answers.

SFGATE also reported that authorities in the county were exhuming unidentified decedents for DNA testing.

However, the reporting did not establish that any specific exhumation, DNA sample, or genetic genealogy analysis had produced a potential match to Teresa.

Modern forensic identification techniques may provide opportunities that were unavailable in 1979, but their potential usefulness should not be confused with a confirmed breakthrough in this case.

January 20, 2025: The case receives major news coverage

On January 20, 2025, SFGATE published Katie Dowd’s investigative article, A Bay Area mom vanished into thin air. Her story has never been told..

The article included interviews with Teresa’s daughter, her daughter’s husband, and the detective reviewing the investigation.

It also examined the abandoned Volkswagen, the original investigation, the family’s concerns and the possibility of identifying Teresa through modern forensic methods.

The publication brought substantial new visibility to a disappearance that had received little documented contemporary media coverage.

Importantly, the article was a renewed public examination of the case, not an announcement that investigators had determined Teresa’s fate.

Status as of October 19, 2026

As of this review, no publicly confirmed investigative developments after the January 2025 reporting were located.

The California Department of Justice continues to maintain Teresa’s missing-person record. No verified announcement was located establishing that she had been found, that her remains had been identified, or that an arrest had been made in connection with her disappearance.

No case-specific announcement confirming a successful DNA match, genetic genealogy identification, or new criminal charge was found.

This does not necessarily mean investigators have stopped working on the case. Law enforcement agencies may pursue leads without publicly disclosing every investigative step.

The most recent substantial publicly documented investigative activity located during this research remains the 2024 reopening described in SFGATE’s January 2025 article.

Sources: SFGATE, January 2025; California DOJ case record.

A Family Still Waiting for Answers

Teresa McKinley’s disappearance has affected her family across generations.

Her daughters grew up without knowing whether their mother had died, voluntarily left, or experienced an unknown tragedy.

Heather Gonzalez has described the emotional burden of living with that uncertainty and the frustration of seeing so little progress over the years.

The renewed investigation offered her family something that had been largely absent for decades: the possibility that investigators might revisit old evidence, reconsider assumptions and use modern investigative methods to find answers.

Teresa was more than the subject of a missing-person file. She was a mother, an artist and a young woman preparing for a new chapter in her life.

Her disappearance remains unresolved, and the passage of time has not diminished her family’s need to understand what happened.

How to provide information

Anyone with information about Teresa’s disappearance, her movements on September 16, 1979, or her Volkswagen’s presence near Lake Berryessa is encouraged to contact the Vacaville Police Department.

The department’s officially listed contact number is 707-449-5200, and its case reference is 794613.

SFGATE also published a case-related tip number, 707-454-5722, in January 2025. That number is retained below as a historically published case contact, although its current routing has not been independently verified.

Even information that appears minor could help investigators reconstruct Teresa’s movements or clarify what happened to her vehicle.

Until credible evidence establishes otherwise, Teresa Lynn McKinley remains a missing person whose fate is unknown.