Will, we ever find out why Frank Lyle impersonated Mr. Neely? If you do not know, why do you think he impersonated Mr. Neely

In my opinion, Frank Lyle impersonated Mr. Neely in order to gain information from Jessie. Jessie didn't know Mr. Neely, thus, she would be unaware of his death six years before. When Lyle realized that Jessie knew too much, he decided she needed to die.