I am so sorry that happened. I'll bet if you offered a small reward to any student who has information on the theft. Plus did a news story on it. You would find the culprit. It's likely someone who works at or has a child attend the school.
I once had an entire newly planted land scape stolen. I had 5 topiary, dozens of perennials and some nice rocks taken. Three mornings after planting I went out and found holes with trails of soil leading to the road.
It appeared someone pulled up in a truck in the middle of the night and just quickly lifted it up and tossed it in a truck then away they went. 😕 It's very hurtful.
Ever since that lesson. I only put a few things in each year where they might be seen and make sure they are established before moving forward.
All expensive trees I chain to a concrete anchor until they are established. I also put "video surveillance" signs around.
