If the owner of the computer has been arrested and is the subject of a criminal investigation, he can not be forced to give the police a password because it is a violation of his rights protected by the 5th amendment.
A typical Miranda warning includes the language
You have the right to remain silent (when being questioned).
Analysis
Kirschner and Doe support this answer.
Boucher does not apply because the defendant waived 5th amendment protection by initially cooperating. Fricosu does not apply because the encryption issue was mooted by a third party providing the password. In both cases, the 5th amendment was used to protect the defendant from being forced to produce the password. Another hurdle is the non-rebuttable assertion that the defendant might not remember the password. As Fricosu pointed out.
Disclaimer
I am not an attorney. I am not your attorney. This advice is not intended to apply to your specific situation. DO NOT FOLLOW IT. If you have a legal problem, ask a real lawyer not the internet.
