One way to find out without intruding on his privacy..
Keep employing him for the interim and see if things start disappearing.
Like money from you van / wallet, items that you have that can be sold easily.
Customers might call you to ask if saw something that they now find missing. Like a wallet or purse!!!
Most addicts ( not saying your apprentice is and addict ) are fine when they can maintain their habit financially, it's when they can't maintain their habit financially they become a problem.
Or just see if they fall down the toilet trainspotting style.
Come on not every body is a stereo type. Do you walk round upside down with a cork hat and saying strewth whilst swigging your fosters.
I started smoking weed when I was 16 between the age of 17 and 21 I probably took enough pills to kill off the kangaroo population chuck in a bit of speed over that time, always turned down smack as didnt look my kind of thing and couldn't afford coke back then. I cut down most drugs at age 21 apart from weed because my son was born and still did the occasional pill and then the odd bit of coke as we were starting to get that a bit cheaper.
A large amount of my friends still use drugs recreationally and out of everybody I used to hang around with back then 2 became heroin addicts over the space of 2 years and I know of 1 coke addict. Out of those 3 they all still worked to fund their habit and never stole a penny to fund their habit.
I know of 2 people that got sent to prison and blamed having to steal on being an addict but they were thieving scrotes before and after they were addicts.
The rest of my friends just use drugs and have fun they dont steal, they dont fight, dont hang around in gangs dont carry knives. They just work hard and have fun.
Now let's talk about alcohol I can walk down my local high street and get abused by the local p**s heads, over the last 4 years I have buried 5 members of our family 3 of which was solely down to alcohol abuse. Go out on a friday/ Saturday night and the streets are filled with people throwing up, fighting and passed out. And I know of loads ofpeople that alcohol has ruined their lives.
But alcohol is legal so its fine