Hello Venkat,
Like Rajeev Dixit mentioned, does the Appointment Letter cover this aspect?
Also, do you have a Non-Compete Agreement for this position/employee in-place?
Now coming to the Plan-of-Action, I think I will be @ variance with Raj Kumar's suggestion this time.
Had this employee only joined another job while still serving your company, then 'amicable settlement' COULD be one viable option. But in this case, this employee went far from that step. A lot depends on the 'type' & 'extent' of damage he caused to your company--deeming that damage was indeed done.
And another important aspect--what is the reading of your management regarding the timeframe of the damage caused--meaning is the damage limited to the CURRENT set of contracts or does/could it extend to any future ones too? Given that you are into Infra sector, the chances of long-term damage is high, since Infra contracts take a long time to materialize [from start-to-finish]. If such situation is thought realistic, then suggest go legal without hesitation. You mentioned you also have his DIN details--that should suffice to put this guy in the dock. And this is 'irrespective' of whether the Appointment Letter has the relevant clauses OR NOT--can be pursued independently.
This also brings to the fore the culpability of the company where he is the Director now. If you have sufficient proofs/evidence, then you can as well bring the other directors & the company too into the scene legally--in a way to cover your positions in the contracts under scrutiny.
To some extent, this COULD get covered under Industrial espionage clauses--meaning criminal intent--your advocate would be better placed to suggest these aspects.
So, in a nutshell, this IS NOT just a case of an employee working elsewhere but also to do with company confidentiality & business espionage.
All the Best.
Rgds,
TS