At first I thought that they had gained access to the back of my house by traveling over the neighboring rooftops. I now believe that to be false. Black shoe skid marks on my walls where they shimied up are proof enough for me that they just came directly onto my property.
From what I was able to piece together, they used some old concrete blocks that I had innocently left laying around as a stepladder. Although it is not a climb I would want to attempt, I suppose burglars and theives have no such regard for their own personal safety.
The route was the concrete blocks, the hole, the ledge, up to the ledge on the carport roof and then over the small wall that surrounds the second floor.
Once onto the second floor, they had free passage to the back of the house and more pipes via this passageway. The wall on the left is actually the wall of the house of my neighbor.
I have now painted every exposed piece of pipe on my house and on the cabana. I have also "tied" the pipes together in various spots using cable ties. Finally, I had braces installed around the pipes and screwed into the cement. It may not stop a determined thief, but it is certainly going to slow them down. At least long enough for somebody to hear or notice them anyway.
As a final precaution, I have now stopped access from the front of the house to the back via that passageway. I did so by having this floor to ceiling, lockable gate installed. A pain in the ass for me when I want to get to the front of the house. But a bigger pain in the ass for any would-be bad guys.
There was a slight glitch during the installation. As usual, measurements were slightly off and the door didn't exactly close.
That error has now been fixed. The gate is now securely locked and I am at peace.