MEXIA, Texas - The Texas Department of Public Safety says a Texas state trooper who was shot last week in North Texas will remain on life-support until he is able to be an organ donor.Texas DPS shared the update Monday that after life-saving efforts by Baylor, Scott & White staff, it was determined that Trooper Chad Walker "no longer displays signs of viable brain activity.""This final sacrifice embodies Trooper Walker’s actions throughout his life and service as a Texas Highway Patrol Trooper," says DPS on Twitter. "The Walker family is grateful for the continued support and prayers as they remain at Chad’s side."DOWNLOAD THE FOX 7 AUSTIN NEWS APPWalker was shot after responding to assist a motorist on FM Road 2848, near US Hwy 84 near.