I understand it depends on whether the FBI can show malice, planning and intent, and the size of the damage ($42k in the Siemens case). So in your plumber case

I understand it depends on whether the FBI can show malice, planning and intent, and the size of the damage ($42k in the Siemens case). So in your plumber case it's probably impossible unless it's like a pattern of fraud rather than just one mistreated client. If a plumber actually tried to make a fraudulent business model out of such behaviour, then I could totally believe they might get jail time. Furthermore, if you sue the plumber yourself, that's a civil case and so jail time is not possible at all (the Siemens case was handled by the FBI). I personally do not think that 6 months' jail for stealing $42k from somebody is so severe, to be honest, it's a lot of money.