This is interesting stuff, for sure.

But a key word doesn't appear in TFA: "motive".

No matter how well you hide/burn/dissolve/etc the remains of anyone with whom you have a relationship, you'll be a suspect. You can try to fake an alibi, and obscuring the time of death does help with that. However, any evidence for that having been done may implicate those with motives, because a random serial killer likely wouldn't bother.

That's why most unsolved murders involve ~random selection of victims.