Overview

Last seen: October 3, 2020, at approximately 3:45 a.m.
Last-seen location: Unity, Wisconsin
Age: 27
Remains recovered: November 30, 2024
Recovery location: Private property near County Highway P and Abe Lincoln Road, Town of Brighton, Marathon County, Wisconsin
NamUs #: MP74504
Clark County Sheriff’s Office case #: 2020-14423

Main circumstances: Cassandra Ayon disappeared after leaving a friend’s residence in Unity during the early morning hours of October 3, 2020. Her black 2015 Chevrolet Impala disappeared with her. Investigators ultimately accused her former boyfriend and the father of her child, Jesus Contreras Perez, of stalking and killing her and concealing her body. He was convicted in 2022, but Cassandra remained missing until partial remains were discovered in rural Marathon County in November 2024. Authorities subsequently said they were still investigating possible accomplices and searching for Cassandra’s vehicle. In March 2025, Contreras Perez’s conviction was vacated and the criminal case was reopened for a new trial.

Detailed Case Breakdown

Cassandra Ayon: Wisconsin Mother’s 2020 Disappearance, Discovery of Her Remains and the Continuing Investigation

Brief Case Summary

Last seen: October 3, 2020, at approximately 3:45 a.m.
Last-seen location: Unity, Wisconsin
Age: 27
Remains recovered: November 30, 2024
Recovery location: Private property near County Highway P and Abe Lincoln Road, Town of Brighton, Marathon County, Wisconsin
NamUs #: MP74504
Clark County Sheriff’s Office case #: 2020-14423

Main circumstances: Cassandra Ayon disappeared after leaving a friend’s residence in Unity during the early morning hours of October 3, 2020. Her black 2015 Chevrolet Impala disappeared with her. Investigators ultimately accused her former boyfriend and the father of her child, Jesus Contreras Perez, of stalking and killing her and concealing her body. He was convicted in 2022, but Cassandra remained missing until partial remains were discovered in rural Marathon County in November 2024. Authorities subsequently said they were still investigating possible accomplices and searching for Cassandra’s vehicle. In March 2025, Contreras Perez’s conviction was vacated and the criminal case was reopened for a new trial.

Cassandra Ayon Disappears from Unity, Wisconsin

Cassandra Ayon was 27 years old when she vanished from central Wisconsin in October 2020. Authorities determined that she was last seen at approximately 3:45 a.m. on Saturday, October 3, when she left a friend’s residence in the Unity area.

Cassandra was driving a black 2015 Chevrolet Impala bearing Wisconsin license plate AHZ-2509. She did not return home, and the vehicle disappeared with her.

Her parents reported her missing the following afternoon. Early reports said Cassandra had recently moved into a residence across the street from her parents. When she failed to return home and later failed to report for work, concern quickly grew that something was seriously wrong.

Investigators Focus on Cassandra’s Former Boyfriend

The investigation eventually centered on Jesus Contreras Perez, Cassandra’s former boyfriend and the father of her child.

According to court records and accounts of the criminal investigation, Cassandra and Contreras Perez had an on-and-off relationship that ended shortly before she disappeared. Witnesses told investigators Cassandra had been afraid of him and described allegations of stalking, threats and physical abuse. Witnesses also reported seeing bruises on Cassandra before her disappearance.

Investigators examined Contreras Perez’s activities in the period leading up to Cassandra’s disappearance. According to reporting based on the criminal complaint, internet-search evidence included searches concerning license-plate addresses and firearm silencers. Prosecutors also relied on cellphone-location evidence that they said placed Cassandra and Contreras Perez in close proximity around the time she vanished.

Murder Charges Filed Without Cassandra’s Body

Authorities did not need to recover Cassandra’s remains before pursuing a homicide prosecution.

On June 7, 2021, Wisconsin Department of Justice prosecutors charged Contreras Perez in connection with Cassandra’s disappearance. The charges included first-degree intentional homicide, hiding a corpse and stalking causing bodily harm.

At that point, investigators reported no meaningful indication that Cassandra had voluntarily disappeared. Reporting on the investigation noted there had been no bank activity associated with her, no evidence that she had left the United States and no further activity on her social-media accounts after October 3, 2020.

Cassandra and her Chevrolet Impala remained missing.

2022 Murder Trial and Conviction

After a five-day trial, a Clark County jury found Contreras Perez guilty in June 2022 of first-degree intentional homicide, hiding a corpse and stalking causing bodily harm in connection with Cassandra’s death.

On September 12, 2022, he was sentenced to life imprisonment without eligibility for release. Cassandra’s remains, however, had still not been located.

The conviction therefore answered part of the question of what prosecutors believed happened to Cassandra, but it did not answer one of the most important questions for her family: where she was.

Search for Cassandra Continued After the Conviction

Authorities continued searching for Cassandra after the trial.

The Wisconsin Department of Justice, Clark County Sheriff’s Office and other agencies remained involved in the case. Cassandra’s disappearance also continued to receive attention from missing-person organizations and Wisconsin media.

More than four years after she vanished, that search finally produced a major development.

Cassandra Ayon’s Remains Found in November 2024

On November 30, 2024, Cassandra’s remains were discovered on private property near County Highway P and Abe Lincoln Road in the Town of Brighton, Marathon County.

The Wisconsin Department of Justice publicly announced the identification on December 3, 2024. Authorities said multiple agencies participated in the recovery, including the Wisconsin DOJ, Clark County Sheriff’s Office, Marathon County Sheriff’s Office, Clark County District Attorney’s Office, Marathon County Medical Examiner’s Office, Wisconsin Department of Natural Resources, Wisconsin State Crime Laboratory and Wisconsin State Patrol.

Officials later clarified that a citizen—not a hunter—made the discovery. The location was only several miles from Unity, where Cassandra had last been seen.

The Charley Project subsequently marked Cassandra’s missing-person case as resolved and reported that partial remains had been recovered.

Why Finding Cassandra Did Not End the Investigation

Finding Cassandra’s remains resolved the question of where at least part of her remains had been concealed, but investigators said the broader case was not finished.

In January 2025, the Clark County Sheriff’s Office confirmed that investigators were continuing to look for potential accomplices connected to Cassandra’s death and disappearance. Authorities were also still searching for her black 2015 Chevrolet Impala, Wisconsin plate AHZ-2509.

Marathon County investigators said the property where Cassandra was found was not known to have a connection to either Cassandra or Contreras Perez. Investigators did not publicly establish why that particular property was selected, although its remote location and position along the general route between Unity and the Mosinee area were noted.

That left at least two important investigative questions publicly unresolved: whether anyone else participated in concealing Cassandra or evidence connected with her death, and what happened to her vehicle.

Major Legal Development: 2022 Conviction Vacated

The case took another major turn in March 2025.

Court records cited by Wisconsin media showed that Contreras Perez’s conviction was vacated on March 14, 2025, and the criminal case was reopened. News reports later confirmed that a new trial had been ordered and that Contreras Perez had been transferred back to the Clark County Jail.

Contemporary reports did not publicly explain the precise reason the previous conviction was vacated. Because the 2022 judgment was set aside and a new trial ordered, descriptions of Contreras Perez as currently convicted of Cassandra’s murder became outdated after that court action.

Latest Publicly Located Investigation Information

The latest significant publicly reported developments located for this case concern two separate but related matters.

First, investigators said after Cassandra’s remains were recovered that they were still looking for potential accomplices and Cassandra’s missing Chevrolet Impala. Her car was described as a black 2015 Chevrolet Impala with Wisconsin license plate AHZ-2509.

Second, the criminal prosecution against Jesus Contreras Perez was reopened after his previous conviction was vacated in March 2025 and a new trial was ordered.

No reliable publicly accessible report located through September 20, 2026 established a later final trial outcome. The publicly documented case therefore should not be described simply as a closed 2022 murder conviction. Cassandra has been found, but the later court action and investigators’ search for possible additional participants and her vehicle are important parts of the continuing story.

Anyone with information about Cassandra Ayon’s case, her missing vehicle or other people who may have been involved should contact the Clark County Sheriff’s Office at 715-743-3157.