Markham saw the shooting.
Scoggins and the two Davis girls saw the same man seen by Markham.
Callaway and Guinyard saw the same man seen by Scoggins and the two Davis girls.
Reynolds, Patterson and Russell saw the same man seen by Callaway and Guinyard.
Therefore, witnesses "a block away from the crime scene" saw the killer.
Your assumption that they all saw the same man is unwarranted.
No, you're simply in denial.