with the recent JonBenet Ramsey documentary, many people now feel Burke was the killer. Since he was only 9 yrs old, he could not be charged in Colorado since the minimum age was 10 yrs old at the time (under that age a juvenile cannot commit a crime, so no crime occurred??). His parents were indicted as accessories (perhaps not the exact term) but never brought to trial. Many wonder why - is it possible that due to shielding laws, no evidence against Burke could be introduced (due to his age or the fact he was not being charged) and therefore there was very little that could be presented in court? Can an adult be an accessory to a 'non-crime' if Burke is completely shielded, and in essence no crime was ever committed in the first place?
In general, a guilty action also requires a mens rea, or guilty mind, in order to be guilty of a crime. A child who is too young to form an intent to commit a crime cannot be guilty of a crime. The toddler who finds a loaded gun and shoots someone isn't guilty of assault or murder because the toddler couldn't have formed the intent to commit the crime.
Under the more modern Model Penal Code definitions, Strict liability laws are applied regardless of intent, but negligent, reckless, knowing, and purposeful states of mind all require some level of intent, and again, a child is unable to form this intent.
The defense of infancy is a defense against the formation of a mens rea by a child's age. In English common law, under the age of 7, infancy was a complete defense. Age 7 to 14, infancy was a rebuttable presumption, and over 14 were presumed capable. In the US, some laws set different ages, as corrected in the comments, CRS 18-1-801 states that "No child under ten years of age shall be found guilty of any offense."