A Mississippi man is charged with killing his mother after authorities allegedly found him trying to flush pieces of her flesh down a toilet in what a local sheriff called one of “the most heinous crimes that I’ve ever witnessed in my entire life.” Zachary Lavel Jackson Jr., 29, faces charges of first-degree murder, second-degree murder, mayhem and tampering with evidence in connection with the death of his mother, Lana Brown Bradley, 62, a retired teacher. The Adams County Sheriff’s Office said deputies initially responded April 4 to Bradley’s home in Natchez, after her relatives reported her missing. Jackson was initially identified as a family member of Bradley before investigators confirmed he was her son. “This is by far the most heinous crime that I’ve ever witnessed in my entire life. We weren’t out there that day; this was one of those things when we walked up. This was one of those cases that you will never, ever forget in your life.…