My Father’s theory was that Oswald was told that Tippet would be his ride out. Tippet was to kill Oswald and be the hero , unfortunately for him, he got outdrawn. Oswald then had no way out and went to the movies.
There's a lot about the Tippit murder that doesn't add up. Conveniently, Oswald's wallet (one of them anyways) was conveniently dropped at Tippit's murder scene..and included documentation with the alias (Alex Hidell) that could neatly be tied to the Carcano found in the school book depository.
A longer video (1:15:00) with some speculation, but also a lot of interesting documentation:
https://www.youtube.com/watch?v=aWamvhd9Y3U