By cops I meant FBI/... And the way this is done is you notify the cops first and then coordinate with them if needed. It's not like Twitter learned about this 5 minutes before.

Okay, so does it really happen?

To me it sounds like it’s a civil case where domain specialists need to prove the wrongdoing in court.

It is absolutely the case that employers can and do involve Federal law enforcement when they believe an employee has committed a Federal crime.

The FBI obviously doesn't enforce internal company policies. However, if the company has evidence that the employee is engaging in serious violations of the Computer Fraud and Abuse Act (CFAA) of 1986, or engaging in espionage for a foreign power, then the FBI might send agents to investigate.

Depends on who is doing the complaining, but yes there is precedent to arresting an employee for "theft of trade secrets" [1]

1. https://en.wikipedia.org/wiki/Sergey_Aleynikov

Was this page written by his lawyer? It seems like he downloaded source code from his employer and gave it to some other company.

It seems like he largely got off on what is effectively a technicality, but I doubt anyone would seriously argue what he did _should_ be legal.