After an Oregon State Trooper lost his battle with cancer, his friends created a challenge to honor his memory. lost his battle with cancer on July 22, 2016. His good friend and Colorado State Trooper Jeremiah Sharp created The Greg Walker Challenge to take Trooper Walker's OSP challenge coin across the country. The goal is to get a photo of the challenge coin in the hands of troopers in 49 states. On Sunday, the challenge coin made it to the Indiana-Ohio border where Indiana State Trooper Eric Fields and Ohio State Trooper Steve Ilo were pictured with the coin on I-70. “When the coin has completed the journey, another recipient will follow. Trooper Walker's Challenge will remain a movement in Greg's honor, to recognize the challenge of other Law Enforcement Professionals who are fighting for their lives," the Facebook page reads.