Overview

• Full name: Andrew Paul Mantheiy
• Age at disappearance: 16 years old (some databases list 17)
• Date of birth: June 15, 1960
• Date last seen: May 19, 1977
• Last known location: Interstate 5, Redding, California
• City: Redding
• County: Shasta County
• State: California
• Case classification: Endangered missing person
• Current status: Missing; unresolved
• NamUs identification number: MP23609
• Investigating agency: Shasta County Sheriff’s Office
• Reported sheriff’s case number: 77-16371 (historical secondary-source listing)

Circumstances: Andrew was reportedly last observed walking northbound near Interstate 5 in Redding. He was never heard from again, and publicly available case descriptions provide little information about his intended destination or what may have happened afterward.

Detailed Case Breakdown

Andrew Paul Mantheiy: The Unsolved 1977 Disappearance of a Teenager in Redding, California

On May 19, 1977, Andrew Paul Mantheiy disappeared in Redding, California, after reportedly being seen walking northbound along Interstate 5. He was just 16 years old, and his disappearance would become a decades-long mystery.

Nearly five decades later, fundamental questions remain unanswered. Where was Andrew going? What happened after he was last seen near the highway? And could advances in missing-person identification technology eventually help determine his fate?

Andrew’s case remains an unresolved missing-person investigation. Publicly available information about the circumstances is limited, and there is no verified evidence establishing that he was murdered, abducted, or deliberately disappeared.

Case Summary

• Full name: Andrew Paul Mantheiy
• Age at disappearance: 16 years old (some databases list 17)
• Date of birth: June 15, 1960
• Date last seen: May 19, 1977
• Last known location: Interstate 5, Redding, California
• City: Redding
• County: Shasta County
• State: California
• Case classification: Endangered missing person
• Current status: Missing; unresolved
• NamUs identification number: MP23609
• Investigating agency: Shasta County Sheriff’s Office
• Reported sheriff’s case number: 77-16371 (historical secondary-source listing)

Circumstances: Andrew was reportedly last observed walking northbound near Interstate 5 in Redding. He was never heard from again, and publicly available case descriptions provide little information about his intended destination or what may have happened afterward.

Sources: Websleuths case documentation; Redding missing-person listing.

Background: Who Was Andrew Paul Mantheiy?

Andrew Paul Mantheiy was born on June 15, 1960. Although he disappeared in Northern California, available case information indicates that he was originally from Texas.

His early life remains largely undocumented in publicly accessible accounts. There is little verified information about his education, friendships, family circumstances, or how long he had been living in California before his disappearance.

One significant detail appears in historical missing-person summaries: Andrew’s mother died in July 1976, approximately ten months before he vanished.

The loss occurred during his teenage years, but no verified investigative source establishes that his mother’s death caused or contributed to his disappearance. Any connection between these events remains speculative.

Andrew’s Physical Description

At the time he disappeared, Andrew was described as:

• Race: White
• Hair: Brown
• Eyes: Blue
• Height: Approximately 5 feet 9 inches to 5 feet 10 inches
• Weight: Approximately 125 pounds
• Age: 16, based on the reported date of birth

Publicly available summaries do not establish what clothing Andrew was wearing when he disappeared. They also do not provide confirmed distinguishing marks, tattoos, scars, or information about belongings he may have carried.

These details appear in historical case documentation reproduced by Websleuths and in the 2017 Underground Mysteries article.

The Disappearance on May 19, 1977

Thursday, May 19, 1977, is the last documented date associated with Andrew Mantheiy’s disappearance.

According to missing-person case summaries, Andrew was last seen walking northbound along Interstate 5 in Redding, California.

Interstate 5 is a major north-south transportation corridor extending through California and into Oregon and Washington. The highway’s importance as a travel route makes Andrew’s last reported location particularly relevant, but it does not establish that he was hitchhiking, attempting to leave the area, or traveling toward a particular destination.

Public case descriptions do not establish the precise time of the sighting, the identity of the person who observed Andrew, or whether he was alone.

Nor do they confirm whether he had arranged transportation, intended to meet someone, or planned to return home.

After that reported sighting, Andrew was never seen or heard from again, according to the available missing-person accounts.

What Happened After the Last Sighting?

The publicly documented sequence ends almost immediately after Andrew was reportedly seen near the highway.

No verified source reviewed for this article establishes that he boarded a vehicle, contacted another person, reached a particular destination, or was observed at another location.

The absence of those details leaves investigators and the public with an unusually limited picture of his final known movements.

Source: Andrew Mantheiy case discussion and historical records.

Investigation History and Available Evidence

Shasta County Sheriff’s Office

The Shasta County Sheriff’s Office is identified as the investigating agency in historical case information.

A reproduced agency listing identifies sheriff’s case number 77-16371. That number should be treated as a historical secondary-source reference until confirmed against a current sheriff’s office record.

The public record does not provide a detailed chronology of the original investigation. Specific information about initial searches, interviews, evidence collection, or investigative decisions was not located in the reviewed material.

This does not mean those activities never occurred. It means their details could not be independently verified from accessible sources.

Physical Evidence and Forensic Identification

No publicly confirmed physical evidence directly explaining Andrew’s disappearance was identified in the reviewed sources.

There were no verified reports of recovered clothing, personal belongings, a vehicle associated with the disappearance, or forensic evidence establishing criminal involvement.

A July 15, 2025, community research article reported that Andrew’s NamUs information indicated DNA was available for comparison, while dental records and fingerprints were not.

That is a secondary-source description, not a newly announced forensic breakthrough. The availability of DNA comparison information does not mean that a match has been made or that Andrew’s remains have been located.

The same article discussed unidentified-person exclusions associated with Andrew’s NamUs record. Such exclusions can be part of a long-term identification process, but they should not be mistaken for proof of what happened to him.

Missing and Unidentified Persons Databases

Andrew has been documented in missing-person resources, including a historical NamUs listing identified as MP23609.

The National Missing and Unidentified Persons System supports efforts to compare missing-person information with unidentified individuals and human remains.

The California Department of Justice also maintains a Missing and Unidentified Persons Section and a Missing Persons DNA Program. These programs assist law enforcement with identification and missing-person investigations.

The existence of those programs does not establish that a particular testing method or investigative procedure has been performed in Andrew’s case.

Sources: Cold Cases of the Golden Coast; California Department of Justice.

Theories and Unresolved Questions

Because so little has been publicly documented about Andrew’s disappearance, several possibilities remain open. None should be treated as an established explanation.

Did Andrew Leave Redding Voluntarily?

Andrew’s reported location near Interstate 5 raises the possibility that he intended to travel.

However, there is no verified evidence establishing that he planned to leave Redding permanently, was running away, or had a specific destination.

Walking near a highway does not, by itself, demonstrate an intention to hitchhike or disappear.

Could Andrew Have Encountered Foul Play?

The possibility of criminal involvement cannot be ruled out based on the limited public information.

However, no suspect, person of interest, abduction, or homicide has been publicly established in the sources reviewed.

There is also no verified evidence linking Andrew’s disappearance to a particular offender or another crime.

For these reasons, describing the case as a confirmed homicide would be inaccurate.

Could an Accident Explain His Disappearance?

An accidental death or other emergency is another theoretical possibility, particularly given the reported highway location.

Nevertheless, no confirmed accident, recovered remains, or other physical evidence was located that connects such an event to Andrew.

Could Andrew Be an Unidentified Person?

One question in long-term missing-person investigations is whether an individual may have remained unidentified after death.

Comparison of missing-person records with unidentified-person cases is therefore relevant to Andrew’s case.

A community researcher reported numerous NamUs exclusions associated with Andrew’s record as of July 2025. These reported exclusions are not positive identifications and do not establish his fate.

The central unresolved question remains what happened to Andrew after his last reported sighting on May 19, 1977.

Latest Publicly Available Investigative Updates

Research reviewed through October 18, 2026

July 15, 2025: Renewed Community Documentation

On July 15, 2025, the blog Cold Cases of the Golden Coast published a retrospective titled “The Disappearance of Andrew Paul Mantheiy, May 1977.”

The article summarized Andrew’s disappearance, personal description, historical family information, and reported NamUs identification data.

It also discussed unidentified-person exclusions and reported that DNA comparison information was available.

This publication demonstrates continuing public interest in Andrew’s disappearance. However, it was a community research article, not an official law enforcement announcement or confirmation of a new lead.

Source: Cold Cases of the Golden Coast.

Status as of October 2026

No publicly confirmed recent investigative developments were located in the sources reviewed through October 18, 2026.

Specifically, the research did not identify a verified announcement of an arrest, criminal charge, identified suspect, recovered remains, positive DNA identification, or resolution of Andrew’s disappearance.

No new official investigative statement specifically addressing Andrew’s case was located.

The absence of a publicly announced development does not necessarily mean investigators have stopped working on the case. Law enforcement may possess information that has not been publicly released.

Andrew should continue to be described as missing unless an authoritative source establishes a change in his status.

Conclusion: Remembering Andrew Paul Mantheiy

Andrew Paul Mantheiy was only 16 when he disappeared near Interstate 5 in Redding, California, on May 19, 1977.

The known details of his disappearance are few. His reported final sighting, his Texas background, and the death of his mother the previous year provide fragments of a life, but they do not explain what happened to him.

For almost half a century, Andrew’s fate has remained uncertain.

Someone may still possess information about his movements, his acquaintances, his intended destination, or an encounter that occurred around the time he vanished.

Even information that seemed insignificant in 1977 could be worth reporting to investigators today.

Anyone with credible information about Andrew Paul Mantheiy’s disappearance is encouraged to contact the Shasta County Sheriff’s Office at (530) 245-6000, or the California Missing Children Clearinghouse at 1-800-222-3463.

Tips should be reported to law enforcement rather than investigated independently or used to publicly accuse individuals without evidence.

Andrew’s disappearance remains an unanswered question, and his case deserves continued attention.