Fake emails/tracing IP?

I sent out some fake comment letters for my brother to his place of business. I did it using psuedo email addresses and names, however they investigated it thinking all these compliment letters had to be fake when staff starting complaining about my brother (most complemented him, and a couple were negative towards other staff), now they say they have the "results to the investigation" and I am concerned that they traced my IP address back to my home, is this possible? What kind of trouble could I get into for this? (21 male BC Canada) He doesn't find out the results until he returns to work in 4weeks, he is a manager at a restuarant.