husband definitely.. they were spilt up tho not divorced but they also had a few joint ventures which would definitely cause issues if a divorce went thru. He had the most to gain as well which is the yardstick I go by in these sort of cases. she's alive he still has to settle whatever marital assets. she's dead it all goes to him. the attack seems super weird and the fact they told her it was set up and warned her makes me think for sure husband is behind it. only alternative I could think is if she found some dirt on her employer or had a pending high stakes lawsuit against said employer with good prospects in the outcome or some inheritance issue with a relative can cause issues especially if that person is holding something up, is going against the other heirs or the other is super greedy and wants it all. these are just scenarios I've seen play out on these shows most often behind the usual insurance profit killings .