Absconding Employee settlement Dues even though not working for a single Day

Hi,
An Employee absconded from IT firm after just after documentation, informed HR saying that he wont be able to continue Joining due to some reasons.
Recieved multiple show-cause notice for Absentism, and Employee replied with Email sent to HR saying that he have already informed HR about not joining the Company.
After 6 months Employee Received Termination Letter, after the Date of Termination Letter after 2-Months now Company has sent Settle Dues of a 5-digit amount and threatening to file a legal case.
what should the Employee do at this scenario.
Note:
Employee didn't even collect his ID card,
Informed HR about not continuing to Join with the Company,
Didn't Receive any Salary/PF or any Monetary Benefits.

Hi,
As part of disciplinary proceedings, to close the file HR might have served those letters. Even if the employee signed service agreement /bond/training agreement there will not be any legality as he was not part of the Company not even one day. However if any security cheques issued, need to handle it carefully.

Thanks V.M.Lakshminarayanan,
can u please explain about security cheques?
is is about the blank cheques?

Hi,
As part of service agreement/training agreement companies use to collect security cheques undated but signed favouring the company with a condition to deposit the cheque in the bank in case of violation of the terms and conditions by the employee before the completion of bond period. Cheques if deposited and bounced Companies can file criminal case for cheque bounce which needs to be handled carefully. However even if cheque submitted I don't think employer will deposit as there was not service period involved and the employee left immediately after joining.

When the appointee has not at all joined the organization, how the employer can assume disciplinary control over him and issue termination orders?
Better the poster simply ignores the legal notice or send a suitable reply setting forth that the organization has no locus standi to issue such a notice.