Frankly, I think Bharghavi gave her opinions based on how she saw the 'readings' of the situation—you need not have come over her like a ton of bricks... no pun intended, please.
In fact, I think it's this variety and range of angles from which the members of this Forum view a subject/topic/issue that makes this Forum so very lively, informative, and more importantly, educative.
Prioritizing Your Actions
First of all, I think you need to make up your mind on what your priority #1 is. Is it [1] Teaching the Sales Head a lesson for what he did to the company? OR [2] Ensuring he doesn't repeat it at the new company too? OR [3] Safeguarding your company's interest AFTER this fiasco?
Let me explain—if you alert the next company, there are 2 possible scenarios that can arise: maybe they would drop this guy OR they would ignore your inputs [especially if they set up the whole thing]. But can you keep tracking him all through to see which company he would join then and keep alerting every company he intends to join [after all, he, like everyone, needs to work]? Is this realistic and practical?
Perhaps, at a subconscious level, you are mixing up what you really want to avoid at the conscious level—thinking through the 'head' and through the 'heart'? Hope you get the point.
Safeguarding Your Company
The way I see it is this: Your First Priority HAS TO BE to safeguard your company AND ensure the message goes down the line within the company that such behavior wouldn't be tolerated AND would invite severe action from the company.
I would suggest you involve your company advocate ASAP in deciding the next step. While by common sense, his admittance in writing is OK, legally it may not be enough—what if he says in court that he was coerced to give the written statement? It takes a lot more evidence to have a watertight legal case. Another reason why involving your advocate right at this stage is better is such issues can take time to get resolved and also be time-sensitive. If you don't have any company lawyer, you can contact any legal member from this Forum I guess—there are quite a few of them who are capable.
And, like one member suggested, refer the case to the Cybercrimes cell—with your advocate involved all through. This step would also bring out any possible involvement of outsiders [not necessarily the new company], IF ANY. With this single step, you would be handling the issue with the focus on your company's secrets rather than on the individual AND ALSO sending a strong message to other employees.
All the Best.
Regards,
TS