Suppose your child is kidnapped. The kidnappers call you, give you "proof of life" (i.e., irrefutable evidence that they have your child in their custody and that the child is unharmed), and tell you that if you convey any information to law enforcement about the kidnapping they will kill your child. (Otherwise, if you comply with some other demand they will release your child unharmed at a specific date in the future.)
Before long, police determine that your child is missing and you are detained to explain what is going on. You conclude that it is in your child's best interest to comply with the kidnappers' demands. Therefore, you refuse to talk to the police. Are you guilty of obstruction of justice?
Before long, the police through other means determine that your child was kidnapped and is being held for ransom, which the kidnappers will demand of you. Once again the police detain you and demand that you cooperate by giving them information that may help them find the kidnappers and your child. Once again you conclude that the best course of action is to refuse to convey any information to law enforcement. Could you be charged with any crime?
Eventually, using other information, law enforcement tracks down the kidnappers, who kill your child. Are you now guilty of aiding and abetting either the crime of kidnapping or the crime of murder (of your child)? If you truly had no involvement other than as the parent and target of the criminals, can you be named as an accessory or conspirator for failing to provide law enforcement with information relevant to the ongoing crime of kidnapping?