The 55 Year Old Cold Case of Joseph Mulvaney

In 1992, a Wyoming man opened a padlocked military footlocker left in his shed by a neighbor six years earlier. Inside, he found the skeletal remains of a man shot in the head, wrapped in a grocery bag. It would take decades to pass and a DNA breakthrough to reveal that the 'man in the box' was Joseph Mulvaney—a father who had been murdered.

Sources: 

1) https://www.kulr8.com/news/55-year-old-cold-case-murder-solved-in-wyoming/article_583c0f3f-1ca9-5dc8-b905-1f35d93d3f3c.html
2) https://fox2now.com/news/true-crime/bones-in-a-box-mystery-of-missing-illinois-veteran-solved/
3) https://www.wyomilitary.wyo.gov/19_088/
4) https://www.findagrave.com/memorial/194722282/joseph_junior-mulvaney
5) https://unsolved.com/gallery/skeleton-in-a-box/
6) https://en.wikipedia.org/wiki/Thermopolis,_Wyoming