Justin Mohn decapitated his dad after first shooting him in head with 9mm he bought the day before: DA
Mohn, 32, bought the 9 mm handgun the day before murdering his dad — even giving up a marijuana card to ensure he could buy it, officials said.
The disturbed conspiracy theorist accused of decapitating his dad and then holding up the head in a sick online video had first shot him dead with a gun he bought legally the day before, officials sa…