UPDATE:
Yesterday in the evening when I returned home I found a limping GSD outside my house. By the time I could get it something to eat, it vanished. Moreover the strangest thing I found was that it was running around with a group of street dog. Maybe someone had abandoned it or something. At night I chatted about it with my wife and she said I was day dreaming about the dog. Why would a GSD go with street dogs?
Again today morning I saw it on the road backside of my house. I took my two wheeler and some biscuits. When I offered it some biscuits instead of eating it, it ran away. So disappointed I returned home to find a big surprise
When I had gone to offer it biscuits I had left the main door open. When I returned I found that the GSD was inside the compound of my house. I shut the door offered it biscuits and milk which it ate after a little hesitation. I called out my wife and kids and they were amazed. I got a dog chain from my neighbour who has a Doberman and chained the GSD. It was very obedient but my wife insisted we leave it as its not ours. She was of opinion that if it wishes to stay here he would stay even if main door is open so she opened the door after I removed the chain and the dog went away

She said if it comes back she would let it in. But anyhow it spent about an hour at my house and all of us were thrilled.