Reliving Letter Incase Notice Is Not Served

Hi There,
We had an employee working with us who we hired as fresher. After working for 8 month resigned and requested to release immediately without serving the notice. He was giving reason to some personal family problems.
We have written him email that you have serve the complete notice for getting released properly which he didn't serve and left.
Later he followed up for his full & final and certificates. We have done his full and final and paid gave his cheque which got clear from our account. Please note that finance has deducted some amount for the days he has not serve the notice.
Now he want his reliving letter and exp letter and threatening to file a legal case. We never wanted to do anything wrong to our employee but to ensure that if someone leave atleast serve the complete notice.
Can you please guide us what should be done in this case.

A relieving letter need not be given to anyone who has not completed the relieving formalities and completed notice period. However, it seems that you have waived off his notice period, else how did you give him his full and final settlement. If you have deducted salary for motive days not complete, then you are considering payment in liu of notice period. In that case, you might as well issue the relieving letter
You are free to mention both in the experience letter and relieving letter that he has not completed his notice period, etc.