Just a thought, I have heard of a program for ASD children, I know he hasn't been diagnosed and my advice there is to keep looking for the right doctor, perhaps even calling an ASD association with some references of people who deal with ASD professionally to help, never give up that part. but my thought is a service animal. I know that Paws with a Cause has one in MI that they just started about 3 years or so ago and the intention was to help keep the child from danger and also to alert the parents immediately when the child was to stray. You might want to check out their website and maybe even call them to find out what organization in your area does the same. :) Hope she finds something that works, i know locks never worked with my son he was too smart and figured out how to open them, even the higher ones lol.

There is the physical aspect to this (keeping your child safe) which many folks have already covered; excellent ideas about locks and then there is the behavior. I had this problem when my son was 4. He ran away all the time and walked into people's houses. He only walked into the houses of our neighbors who were very up-tight about this behavior. My life was constantly turned upside down and this is what I did. My son loved to play outside and we set boundaries which he regularly ignored. One day he was missing for 7 hours and I called the police and we eventually found him; that is when I said "enough is enough".

I set up boundaries for him again and I told him if he stepped outside our property, he would be inside the house all day. Please know that 10 minutes on a chair never worked with my son. So, he went outside and of course did not stay within the boundaries, so I told him he would be in the house for the next 24 hours. I knew my day would be spent chasing him around the house as he would want to go outside. I did not answer the phone, did not do anything that day but chase my son around and kept reminding him that he could not go outside because he did not follow the rules. He sobbed, he had tantrums, we were both exhausted by 9PM that night but the next day I told him what his boundaries were, he followed them. I let him go outside for short increments of time and kept extending them as he followed the rules. The hardest thing is you have to have a consequence that really works; these children are so smart that you have to think of something that tells them you are serious; my heart goes out to your sister; I've been there and was in a panic constantly about where my son was....

http://www.gokeyless.com/product/106/lockey-223... Install this lock it's a double sided keypad combination deadbolt with a key override for the outside. This is the best option because eventually he will learn how to use keys to escape! You need to have it installed by a professional though because it's not an average do it yourself job. You will also need to drill one additional hole in your door. A locksmith is the best professional to install it.

We have the chain locks at the very top of all our doors. We had to put them that high because out 9 year old still wanders away at night (has totally stopped wandering during the day)and he is already 5 ft tall. Not sure what we will do when he can reach them but this works for now and would definitely work for a 4 year old.

double key lock, leash is inhuman like. Alot of times its a fear. My son use to. It will pass hang in there, use a double key lock, that is the type you need the key for opening in the house and out. We did that when my son was a wonderer, during the day kept in door and at night out of sight although close to door for safety reasons nowhere where my son could see.