weed can cause psychotic symptoms while being used: like paranoia, hallucinations and such. But for the average person, it wouldn't make them perminantly schizophrenic.
However, for someone with the schizophrenic gene, using marijuana can start up the schizophrenia, which was lying dormant until the weed was used.
But it sounds like you might have the wrong idea of what schizophrenia is. It is not going on a rampage of hurting people and then not remembering it. A common myth about schizophrenics is that they are violent and that is rarely true. I have schizophrenia myself. My symptoms include, hearing voices, seeing things, dp/dr, Paranoid delusions (ex: believing the government is sending spies out to follow me and scan my brain, believiing the world is an illusion set up to destroy me, believing i can communicate telepathically with trees, etc.)
So,The main symptoms of schizophrenia are, delusions, hallucinations, catatonic or grossly disorganized behavior, disorganized speech/thought, and affective flattenting....Violence is rarely involved.