Sad story.

My step-sister had a friend who’s father died in a similar accident - working under the car with no jackstands and it fell off the jack.

And one time I was working on my ‘81 Accord, trying to loosen the hub nut while it was just on the scissor jack, and I managed to roll the car forward, and off the jack. Thankfully I wasn’t hurt, and only needed a change in underwear..