I don’t see any cuts on their faces nor hear about any cuts at all on them or the kids, and if he was wielding a knife then they make reports to the police to at least get it on record. Interviews with his siblings and an investigation will reveal what is really went on. But I’ll bet my intuition will spell out better than yours.
I share your intuition with these two. They are not frail or weak looking (aside from the dead eyes) they seem stunning ‘normal’ in the mug pix. So ‘normal’ (no remorse, sadness, signs of crying or stresss) that in IMO it keeps with the ‘type’ that could so wantonly disregard the safety and well being of another human (let alone their—at least his—own child).