(HMU means 'hit me up.') McDonald makes sure to type 'ur' instead of the proper 'your.' It's less suspicious that way. 'Hey i liked ur post HMU,' McDonald types. McDonald works for the Washington State Patrol's missing and exploited children task force, partnering with Homeland Security Investigations (HSI) to catch predators in Spokane. It's a post asking if anyone wants to be 'impregnated.' Then McDonald stops and raises his eyebrows. There's one post asking for pictures, but that's not exactly the kind of thing McDonald has is eye out for. He passes by a few posts, the ones sharing random anecdotes or anonymous complaints from their day. The light from his cell phone spotlights his face as he scrolls through looking for sexual predators. Dan McDonald turns the lights off in a conference room and opens up an app called Whisper. Law enforcement officials say parents should talk to their kids about the dangers of social media apps like Snapchat and Whisper.ĭetective Sgt.