Erm.

So. Having knowledge that a crime is about to be committed and doing nothing about it is quite literally the definition of aiding and abetting and accessory before the fact. Helping someone to evade lawful capture is accessory after the fact... Are you really attempting to say that you can walk up to someone and say "hey Mom I committed a murder I'm going to go hide out, the police have listed me as a person of interest and I'm going to go into the forest now" and have that be legal?

Accessory: Someone aiding in or contributing to the commission or concealment of a felony, e.g. by assisting in planning or encouraging another to commit a crime (an accessory before the fact) or by helping another escape arrest or punishment (an accessory after the fact). An accessory, unlike an accomplice, is typically not present when the crime is committed.

Ref: Cornell.