The defendant was arrested for robbery. He was advised of his Miranda rights, searched, and found to be in possession of a small amount of currency. The defendant made no response when the officer asked him where he got the money. At trial, the defendant testified that he met the victim on the day of the robbery but did not commit the crime. He claimed the money found on him belonged to his wife and was for the purpose of purchasing money orders. On cross-examination, the prosecutor asked the defendant why he did not mention these facts to the arresting officer.
Whether the government can inquire into why a suspect remained silent after invoking his right to remain silent?
No. It is not unusual (or inconsistent) for a suspect to remain silent after being advised of his right to do so.
It is a basic principle of the law of evidence that a witness can be impeached with prior inconsistent statements they have made. However, there must be a connection between the initial statement (or lack thereof) and the testimony at trial. In most circumstances, silence does not amount to prior inconsistency (but see Jenkins v. Anderson). The act of silence amounts to a prior inconsistent statement only if it would have been natural to object to the question when it was put to the witness. This was not the case at the time the question was put to the defendant at his arrest. The guilty and innocent alike could find an arrest so intimidating that they choose to remain silent.
422 U.S. 171, 95 S. Ct. 2133 (1975)