Colorado contractor pleads guilty to manslaughter after willfully sending workers into unprotected trench — 23-year-old employee fatally buried

What Happened

In 2021, 23-year-old Marlon Diaz was installing a residential sewer line in Breckenridge, Colorado when the unprotected trench he was working in collapsed and buried him. He died from his injuries. His supervisor and company owner, Peter Dillon of A4S LLC, had sent him and other workers into the excavation knowing it had a history of cave-ins — without requiring any trench protective system, without having a competent person inspect the excavation, and without instructing workers on how to recognize or avoid the hazardous conditions they were in. After Marlon died, Dillon continued to endanger other workers at the same site.

What Went Wrong

OSHA cited A4S LLC for three willful violations in May 2022 — for failing to ensure a competent person inspected the excavation, failing to instruct workers on recognizing unsafe conditions, and failing to have a trench protective system in place. On August 3, 2023, Peter Dillon pleaded guilty to manslaughter and awaited sentencing — a direct consequence of a supervisor’s decision to prioritize speed over the lives of the workers under his charge. The hazard was known. The history of cave-ins at the site was known. The requirement for protection was known. The supervisor sent a 23-year-old into the ground anyway.

The Bottom Line

“Peter Dillon willfully sent Marlon Diaz and other employees at a location with a history of cave-ins to work in unprotected trenches,” said OSHA Regional Administrator Jennifer Rous. A supervisor’s decision — made in minutes, without paperwork or ceremony — ended a 23-year-old’s life and resulted in a manslaughter conviction. Frontline leadership is not a title. It is a daily responsibility that workers’ lives depend on.

Source: https://www.osha.gov/