It is illegal to assist a fugitive in any way.
Accessory to Crime, CRS 18-8-105 Colorado Law states: "A person is
an accessory to a crime if, with intent to hinder, delay or PREVENT the
discovery, detection, apprehension, prosecution, conviction or
punishment of another for the commission of a crime, he renders
assistance to such person." This crime can be up to a Class 4
FELONY, punishable by up to two (2) years in prison and/or a fine up to
Colorado law above is typical for laws in most states. Turn in a
fugitive and you might earn a reward. Harbor them and you might
earn a criminal record.