Just a thought- Both of my boys are autistic. About a year ago one of them (the eldest, 4 years old at the time) slipped outside while we were carrying groceries in. I noticed he was gone perhaps 10 minutes later. We lived in an apartment then. I searched the apartment in about a minute because he is notorious for hiding. He's also non-verbal. I then (in a blind panic) raced outside and scanned the parking lot. I was pregnant with my last child (about 8 months along) and huge. I didn't see him anywhere. The complex was surrounded by an 8ft privacy fence, but is alongside a very busy road.
I spotted a sheriff's deputy parked at another building (complex was crummy). I ran to that car and scared the bejeezus out of the cop inside. I was hysterical! I explained the situation, how small he was and the level of disability, etc... I could barely breathe.
Within 5 more mins I had given him a photo and he'd gotten at least 2 more units on site. My son was found within 20 more mins. He had slipped through a hole in the privacy fence and was petting a stray dog. At the end, when they drove him up in the patrol car I collapsed on my knees (after hyperventilating/crying for 30 mins) and promptly threw up. I think every cop in the county had shown up.
That's what a mother who's child is missing does, she panics and seeks help. IMHO