I listened to one podcast about this and am listening to another one now that has more detail. DD went to college not far from where all this happened.
I think the father is so far into something criminal he can't get out of it. I think the family has been 'untouchable' for so long, getting away with whatever 'bad' things that happened to them, that the father thought he would never get caught. I think he got caught up with some bad people-- the missing money from the law office is why. Why would he need to steal that money and where did it go? He was wealthy so no need to steal it for himself unless he did something with his own money. People in Hampton county are afraid of this family so they're afraid to talk about what they may know.
I think the boys (one or both) were involved in Stephen Smith's murder. Gloria Satterfield's death was not an accident either. The family knows what happened to her. I think she may have overheard or saw something she wasn't supposed to. Supposedly the Murdaugh's homeowners insurance settled the claim with the Satterfield family for $500,000 but I heard last night that claim was never finalized or paid. The younger son was driving the boat at the time of the accident for sure. The Murdaugh family was trying to pin it on one of the other boys.
As far as the mother and son's murders I'm not sure yet. The father is involved somehow. Either he set it up or someone he ticked off did it as retribution. There isn't enough information out there yet. The fact that the mother and son were shot with 2 different guns leads to the speculation that there were 2 shooters involved.