Zylon (PBO) soft armor field failure — Officer Tony Zeppetella, Oceanside CA

Officer Zeppetella's Second Chance Ultima vest with Zylon (PBO) ballistic fiber failed to stop a 9mm round during his murder in 2003. The incident launched a multi-year NIJ + DOJ investigation into PBO degradation under heat and humidity. NIJ 0101.04 certifications for Zylon-containing vests were ultimately revoked. No NIJ-certified vest has contained PBO since.