In the Supergirl Season 3 episode "Midvale", we have an extended flashback featuring a young Kara and Alex attempting to solve the murder of Kenny, one of their classmates. They have determined that one of the teachers had an illicit relationship with a student and are convinced that he is behind the murder.
As they are walking home, they are driven off a bridge by a car, and it's only through Kara's ability to fly that they are saved. While they initially believe that the teacher was responsible, Alex realizes that it's someone else after she learns that he had an alibi.
My question is: why did the true perpetrator decide to run them off the road? He didn't know at the time that Kara and Alex had Kenny's laptop with incriminating photos on it linking him to drug crimes, and so far nobody had even considered that he might be a suspect. Why not just leave things where they were and let the teacher take the fall for murdering Kenny? If Alex and Kara didn't have the laptop (which again, he didn't know about), then he would have gotten away with it.
