Lesson to be learned: Don't lend money to family and expect it to be paid back in a timely manner or at all.
If one has "other responsibilities" a "I do not have money to lend you" and end of story.
There are people who generalize "nursing school" to encompass everything from CNA, medical assistant, phlebotomy......and for profit schools use this to attract a LOT of students, and keep them for as long as they can for as much money as they can.
There are multiple scams involving schools that when done and tons of money, one can not sit for NCLEX because the school is not accredited, or some other thing.
Nurse intern could be a fancy name for a CNA. Who knows? With customer service health care, it could envoke some sort of better feel good image that nurse assistant does.
Bottom line, OP, you lent out money. Once you lend, you have lost control of those funds. Unless you have a loan agreement, that is signed, I am not sure of what could be done. He could say he thought it was a gift. Going forward, if you decide to lend money to anyone, have repayment terms written out and signed so all are on same page. Or in this case, ask for a bill and pay the school directly, after spelling out repayment between you both.
This manic undercover stuff to "out" him....is this getting any of your money back? So now he has a job. Now you ask his plans on repaying you. Even 20 bucks a week is something. Open a dedicated savings account, and ask that he add it to his direct deposit, 20 a week from his pay.
The rest is on him. He also could be a new grad who isn't working at all due to lack of positions. But he has a job. So now he can do something to help get your funds back.
I had a family member I gave a little money to years ago "cause it's family". The person had already dropped out of school. Come to find out they still had loans. Now they live off the system. Anyway, don't mix money and family with an expectation of being paid back.