After twenty seasons of suspense, NCIS finally addressed one of its longest-running mysteries: the true origin of Gibbs’ famous Rule #1 — “Never let suspects stay together.” While Gibbs had always been cagey about where the rules came from, fans were left wondering if they were entirely his creation or something passed down.

In a recent storyline, the team stumbled upon some of Gibbs’ old case files and personal notes, revealing that many of the early rules were actually inspired by lessons he learned from his former mentor, Mike Franks. The twist? Franks had his own informal code, and Gibbs took those rough guidelines and refined them into the numbered rules fans know today.

This reveal gives longtime viewers a new appreciation for Gibbs’ character — not just as a leader, but as someone who carried forward a legacy while shaping it into something uniquely his. It also brought a bit of emotional closure to fans still missing both Gibbs and Franks.

For a show that’s been solving crimes for over two decades, solving this mystery might’ve been the most satisfying one yet.