Pablo pigscobar in the graham effect?

I just started reading the graham effect. I skipped book 4 of the Briar U series because I reaaaaaally wanted some female hockey book, and also the book 4 of Briar U was about some characters that I barely have heard before in previous book and it didn't motivate me much.

Either way, it is me tío Ed in the beginning of the graham effect that they will. Never allow pets anymore because of an incident. I assume it was with Pablo pigscobar (mentioned multiple times in "the play") so I wanted to know if anyone can tell me what happened?

Maybe it is mentioned later in the graham effect book but I am impatient like that