Series/Episode help?

This is a long shot because I don’t remember what show this was or any of the names of the people that it happened to. I think the episode aired at least 4-5 years ago.

What I do remember:

A couple and their adult son were gunned down in the family home. There was at least one other son and I believe another brother and sister.

It turned out the youngest son was the murderer. Everyone was shocked because his life seemed very put together. He was in a navel or Air Force school, but it turned out he had dropped out and was in debt. If I remember right police initially thought it was the other surviving brother, because he was going through some things.

I tried googling details of the case, but can only find similar stories. (Crazy how often this has happened)