IMO, with respect to the Murdaugh double-homicide, there is a seemingly long list of people who might have the potential for motive given past events involving serious injury or death; however, it seems to me that the attempt at spoilage of evidence at PM's college apartment changes things.
That door was left standing open and a property manager reported it to police on July 8, a day after the bodies of PM and MM were discovered. Those who'd have motive and means to do that are a much smaller list as they'd have to: (1) know about PM's college apartment and where it was, (2) have means to gain access without raising alarms or suspicion when doing so, and (3) have reason to suspect there might be evidence there they wanted to spoil (by making custody indeterminable).
The fact that the apartment was not just accessed after PM's death (to remove evidence a person knows to be there), but it was accessed AND the door was left standing open (to spoil evidence a person thinks could possibly be there), IMO points to someone who is making sure their bases are covered to the extent they can. They are introducing "doubt" about any evidence that might be subsequently recovered there.
That seems a fairly intelligent and calculating thought process, so your average dummy wouldn't have developed that plan. It's a risky move, accessing a victim's apartment with a serious murder investigation underway, so involved someone comfortable with taking such a risk or in a position to use others to do so.
I suppose it is possible the double homicide by two separate weapons and the "spoilage of evidence by leaving door left open 2-1/2 hours away" were executed by entirely different parties. But, IMO it is highly improbable. So, while they will conduct their due diligence to legitimately and reasonably exclude some potentially motivated parties from suspicion, I fully expect that the apartment invasion will serve to help LE narrow the list of prospective suspects considerably and soon.
