I’m sure things are very challenging. I had a friend who adopted a 9 year old with fetal alcohol syndrome: she told me she and her husband had to throw out everything they thought they knew about parenting. Their son had the typical FAS prefrontal cortex damage pattern: anger, aggression, difficulty remembering, poor impulse control, defiance. And he stole all the time, sometimes as part of one of those feelings, sometimes just because it made him feel better. Because of the brain damage, he was sometimes unable to remember that he had stolen the item, even when it required considerable effort to get it.
Ultimately they and their family therapist ended up deciding this was a “magpie child”–the therapist’s term for it–and the only solution was that an adult had to be with the child all the time he was not in his room. He was an intelligent, interesting boy, but he also had very real organic brain damage. No combination of rewards and punishments was going to change that.
Sometimes a camera isn’t a deterrent
I bring up this family because one of the things their therapist told them was that in their case surveillance cameras were not a substitute for a person being in the room with the boy, because unlike a child without similar brain damage, the camera would never be a deterrent. He needed to be actively redirected to an acceptable behavior before the act of stealing began.
The therapist told them that it was like living with an Alzheimer’s patient who kept starting fires because he left pans on the stove too long. Neither cameras nor smoke sensors would ever stop the fires from happening. 
First strategy, then technology
Anyway, I think the first step before investing in a lot of equipment is to have a private session with your family counselor and discuss what kind of technology solutions might be helpful for your specific child.
Do you need information (cameras and tracking sensors), deterrence (better locks), management (easier ways to put valued items into secured locations), or is the only option direct supervision? If the therapist has any questions about what the technology can do, this forum can definitely help answer those if they are placed in context.
Technology is always tactical. It’s how you accomplish a particular goal. But whatever your family situation, the first step should be strategic: to decide what kind of goals are going to be helpful in your specific situation.
Are you trying to collect proof that a particular child is stealing something? Are you trying to make a particular object harder to steal? Are you trying to find ways to redirect a child from trying to steal something in the first place? These are three different goals. Technology could help with any of them, but which ones would be valuable for your own family probably requires input from the therapist.
Just a thought…