This is 99% correct! There should be only one change. Instead of...... "Chinese employees of US and European companies were investigated for similar actions to make sure if there was passing classified or business sensitive information back to China or Chinese companies." It is better to write like this: "Chinese employees of the US and European companies were investigated (for similar actions<- is this necessary???) to make sure if they are/were passing classified or business sensitive information back to China or Chinese companies." Also, the last part can be written like this: ...to make sure if there was any passing of classified or business sensitive information back to China or Chinese companies." わかりますか。 ^_^

How can they investigate people 's mind and their hidden information ?

i'm afraid it isn't.