Amid unrest in Ferguson, Missouri Highway Patrol started using secret messaging app

For more than four years, the Missouri State Highway Patrol used a self-destructing text messaging app called Silent Phone, raising concerns about whether it undermined open records laws or thwarted public oversight of law enforcement.

Silent Phone allows users to make phone calls and send encrypted text messages. It is designed so that users can set the time of a text’s deletion at anywhere from one minute to 90 days. The default setting erases texts in three days.

After which it is gone forever.