Yeah. Dont think it was hit on in the TV series, but there is no way the feds would have hired him straight from the coal mines. You have to have previous law enforcement, military, college degree, or a combination of all 3 to get hired
That wasn't true until very recently for the Marshal Service. Marshal's do not hire employees as 1811s they are just deputy marshals. After several years they make 1811/special agent status. Work experience, not necessarily law enforcement related, used to be allowed as a qualifying factor. You could, for instance, use 2 years of college and 2 years of being a clerk to make up the required pre-requisite requirements.
Surprisingly must 1811/special agent positions do not place a high value on previous law enforcement experience. Most want you to have a degree and that is about it. FBI basically wants only CPAs and Lawyers.