San Quentin is a prison located in San Quentin, Calif. Whenever someone is incarcerated within the state, there is a public record of the circumstances surrounding the incarceration, including any court dates and proceedings that occurred. The State of California has a convenient system of record keeping set up that the public can access online, including information about San Quentin's former inmates. By using the resources available through the State of California website, you should be able to find the public records you're looking for.
Visit the State of California "Public Records Searches" page.
Scroll down to the "Crime and Courts" section of the page.
Click on the appropriate link for the type of record you're looking for. For example, you may be able to find public records for the San Quentin ex-inmate by searching through the "Crime Reports" database or by searching records for the California courts.
Go to the "Inmate Locator" page of the State of California website (see Resources) if you have information you can search for directly, such as the inmate's full name or inmate number.