Do not communicate sensitive information about documentation status and immigration details of people you know over any digital devices or on the internet. If it’s something you don’t want to tell ICE, then keep it out of your phone calls, texts, emails, Signal, Snapchat, social media feeds, etc.

If your device is hacked by malware or confiscated by border patrol, the authorities will have access to all your communications there. Instead of using a fingerprint to lock your phone, switch to a passcode, as biometric data is not protected under the Fifth Amendment.

Sources:

https://medium.com/@TheDailyDemand/dont-get-your-undocumented-friends-in-trouble-a-how-to-75a277875daa#.w281jn8j9

https://www.theatlantic.com/technology/archive/2016/05/iphone-fingerprint-search-warrant/480861/