Just because you think someone is guilty, doesn't mean they are....or there just isn't enough to tie them to the case.
This was professionally done. The assassin knew the home, knew where there were nearby security cameras, knew schedules. Nobody understands why a junior detective called it a murder-suicide on the first day, but I remember a lot of people questioning that. It really didn't make any sense. Barry Sherman wasn't exactly loved. He fucked over a lot of people, including his own family. He filed many lawsuits over the years, and likely pissed off a ton.
Now, I listened to the first few episodes of the Billionaire Murders podcast, but the son could definitely be a suspect. However, the scene had a huge lack of evidence. There are tons of motive, but nothing worthy of an arrest...