Going through your post regarding the excess salary received from your employer after resignation:
It seems that there was a lack of attention to detail, or you can term it as a human error, that while processing the salary for active employees, your name was considered even though you had left the company.
If they have transferred your salary via the bank account that was opened by them during your joining, then they have valid proof that they made a payment to you, which can make their case more powerful in labor court.
Also, you should consider on humanitarian grounds the amount of pressure that person will be facing for wrongly processing your salary. My suggestion would be to pay back whatever amount they have credited to your bank account.
Regards,
Dev