Legal Question in Criminal Law in New York

At common law there was a called crime of misprision of a felony that consisted in failure to report a felony of which a person became aware. There is no similar law in New York.

Strictly speaking, it is not a crime in New York State to intentionally withhold knowledge or information one has as to the identity of person who committed a crime. So, if a thief has confessed some crime to you or even if you saw him actually commit the crime, it is not then a crime for you to refuse to answer questions about this matter put to you by the police or another citizen. Generally speaking, you never have to tell the police anything including things that incriminate others. The main exception is criminal contempt for refusing to be sworn or offer testimony before a court or a grand jury. If you are summoned to testify in court or before the grand jury through use of a subpoena or a material witness order, you may be required to give testimony against another person, unless there is some legal privilege you can successfully invoke to prevent this. However, outside a judicial context, no such compulsion exists in New York, and you have the right to hold your tongue.

Keep in mind that there is a large difference between refusing to say anything, which is almost always safe, and giving false or misleading information, which can open a person up to prosecution in a wide range of situations.