Claude Lescelleur, a 51-year-old engineer, overdosed on May 13, 2014 – one week after the Roche offices were raided.
UPAC investigators had also seized documents from Gaspé city hall. Investigators were looking into allegations of illegal provincial Liberal party fundraising.
Coroner Jean-François Roy found Lescelleur's doctor had prescribed him antidepressants and sedatives because of a breakup months before the raid.
Roy's report states Lescelleur's mood had improved.
However, the corruption investigation then caused Lescelleur a "great amount" of stress, the coroner found.