UPDATE:
the witness who called the police were not the person who aided and abetted the parents. Police are set to find and arrest whoever helped them.
I don't know what I'd have to be offered to hide someone accused of
manslaughter. Pretty sure that shit's a felony.
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This CNN article goes into more detail why these parents were charged with manslaughter for handing their child a gun, when this is America and that basically never happens.
Read if you want, I'll mention one part is "the parents were shown a picture their son had drawn of someone shot to death and him laughing, and didn't think to check if that same son had the gun on him right there on the spot".
It's going to be an uphill struggle, because Michigan has really lax gun laws. If you're not required by law to lock up your gun, it's harder to charge someone with a crime for not locking up their gun.