Passage: "Miranda warnings inform a person in custody of certain rights, including the right to remain silent and the right to an attorney. The warnings must generally be given before a custodial interrogation. Statements obtained in violation of these rules may be excluded from evidence." According to the passage, when must Miranda warnings generally be given?

1. After a conviction
2. Before a custodial interrogation
3. Only during a trial
4. Whenever an officer chooses