I'm stumped. If FG was aggressive by nature I think EG would leave. Financially secure, childless, blah, blah, blah.
There are scenarios where FG isn't directly responsible for DS's passing but still culpable for lesser crimes.
Say DS were getting prescription pain-killers after her surgery and throughout her rehab. Eventually, the doctor cuts her off. Maybe she goes back to him when the ankle/leg acts up, and he writes her a one-time, "NO REFILLS", 30 day supply. Maybe she doctor shops a bit. Who knows.
Lower leg injuries, especially foot/ankle, are insanely difficult to ever get to heal completely. And if you're an active person, hiking, biking, running etc, you can re-aggravate the previous injury from time to time and experience the pain you thought you'd left behind.
Possible that DS ventured into other avenues to get something for her pain from time to time. Doesn't have to be street stuff or anything like that. Tho the image some people have of your average street opiate user (Kurt Cobain or whatever) is prolly not what the typical user looks like today, and maybe not even in days gone by.
But without even going to the street-level, one could see someone who had previously been taking opiate type painkillers sometimes wanting or needing them (for pain or for pleasure, no judging).
And if they met someone with a wife who was battling cancer. And that someone with a house full of cancer meds maybe wanted to help DS out-- maybe b/c he liked DS and wanted to get to know her better and that was a way to get to be around DS, an in? Or maybe just because he empathized with her pain and the difficulty of getting proper pain meds from MD's nowadays.
DS maybe goes hiking or participates in outdoor activities thanksgiving weekend. Her previous injury starts acting up, causing pain. [Or maybe she just liked the stuff, anything's possible ] She wants to either manage the pain or maybe just for fun, she stops by POI/FG's to get some pain-meds.
Perhaps she hasn't had any in a while. She's there and immediately takes whatever's available (oxy, liquid hydrocodone, fentanyl)--either because she wants the pain to go away. or to have fun. whatever the reason.
DS is at FG's house. DS, perhaps with a lowered tolerance, takes too much of something and....FG panics and instead of dialing 911, he Lauren Spierer's DS.
His wife comes back. Asks what's up with the DS situation. FG makes a full confession to his wife and pleads with her not to turn him in. Maybe he notes that he's a black male who'll be dealt with extra harshly & not be given any breaks by the criminal justice system and public opinion. His wife thinks it over, and they get a lawyer together and decide to keep quiet and wait it out.
if they do eventually bust him, he can still explain what happened; and a good ME should be able to back-up his story. Depending on how much time has passed before the ME gets to do his or her thing.
The above, of course, could also be concomitant to an actual affair; but not necessarily so.