One of the main philosophies of John Locke is that our consciousness is formed by the memories and experience that we have had. Leonard Shelby cannot remember anything that has happened since the death of his wife, so according to Locke’s viewpoint he should have remained the exact same person since then. But over the course of the film it has become obvious that Leonard has changed, he has gone from a mild-mannered insurance investigator to a cold-blooded killer. And even though Leonard cannot remember all the killings he has done, they still seem to have affected him in some way. The fact that he is so willing to use his condition to set himself up to kill Teddy says something about how his psyche has changed since the attack on his wife. His lust for revenge and all of the murders he has committed has turned Leonard into a remorseless machine.
According to Locke, Leonard is still guilty of committing those crimes because, although he cannot consciously remember them, they have still changed him as a person. He is no longer the innocent victim, but instead an executioner. They have also changed how the audience percieves him. Initially Leonard can be seen as a sympathetic character, a man trying to overcome his condition and gain vengeance for his murdered wife. After the film we realize that the shooting of Teddy was all a setup and that there is now no stopping Leonard.