206 Cases Solved. Advancing justice for missing persons, unsolved homicides, unidentified and unclaimed remains.

Mark Harnish

Death by Force
Case Description
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On the quiet morning of November 19, 1978, a West Springfield police officer on patrol happened upon a grim scene at a rest stop off Route 5. Mark Harnish, a 20-year-old Caucasian male, and his companion, 18-year-old Theresa Marcoux, were found deceased just over a guardrail from Harnish's green Dodge pickup truck. Both had suffered multiple gunshot wounds. The truck's driver-side window was shattered, and blood was visible in and around the vehicle, a silent testament to the violence that had o ...Read More
Links to Additional Sources (9)
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  • reddit: r/UnsolvedMurders - Today is 42-year anniversary of the murders of Theresa Marcoux and Mark Harnish
  • Florida man being held in decades-old Massachusetts double murder
    •     ...View 7 additional sources
    Victim Details

    Mark Harnish

    Male

    White / Caucasian

    West Springfield

    MA

    1978-11-19

    20

    Mark

    Harnish

    11/08/2025

    Forum Posts (2)
    I’ve been following the Marcoux and Harnish case for a while, and I can’t help but feel for thei... ...Read More
    03/07/2024
    Hey everyone, I just wanted to chime in on the recent developments in the Marcoux and Harnish murder... ...Read More
    11/02/2023
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