Curiosity killed the cat. But not even cats.
To always lock and unlock the mobile is a pain in the neck and actually not necessary. Except for the people in the personal environment nobody has access. But can you really trust them? Does your Girlfriend or Boyfriend read your Email/SMS at an unobserved moment? Nobody watched it. Really nobody? There is a witness of curiosity.
The WitnessApp on your Android Mobile! It logs every unlock event and at your request it takes unnoticeable a picture.
And .... gotcha ... or ... honest people.
This version has the following additional features compared to Witness Lite:
+ invisible image capture
+ invisible application capture
+ hide taken images from gallery
+ protect the app with a password
+ control image capture via time restrictions