How Secure is the pin Lock Screen on Android 4.4?

[AC Question]

I recently noticed some one stole a old back up LG Optimus Pro that i don't use anymore but kept incase i need a back up. There is some very important info on their that could lead to identify theft and all my passwords and photos. It has a lock screen on it. How easy is it to by pass this screen and access my private files? I'm hoping it was just stolen and will be factory reset, but want to know the risks. Thanks

 

[the tall guy]

Hi, unless the person who took the device knows your password, I'd say it's very secure.