This app was mentioned in 1 comment, with an average of 3.00 upvotes
If you're going to go this route, use an app that records directly to some cloud-based storage so they can't just take/break your phone & delete it.
Here's one: https://play.google.com/store/apps/details?id=net.simplylogic.android.cloudcam&hl=en
I've never used it, and am not endorsing it, but it's an idea of what I'm saying.