How to secure a project from spies?

Question

Information Security

There was a question about the security of the project.
Imagine that a team of trusted people is developing a project. Some developments, ideas and their implementation have already appeared. But, it is required to expand the composition of the team, to hire a qualified specialist in a certain area. How to protect the project from theft of developments, ideas, etc. Any ideas or proven methods?

Answer 1

NDA sign with mercenaries.

Answer 2

DLP system can help.
Not advertising, but I really like the functionality of this one, it also makes sense to look at this one. Employees must enter into a confidentiality agreement.

Answer 3

let's access only the necessary part of the information about the project. The NDA is good, but are you ready to go to court?

Answer 4

Benefits from working with you should be greater than from leaving
First, entrust the person with a completely different project / database (having little value for you and an average price in the market). Will not leave / will not sell - then you can believe