A single recording, produced by the victim, from a system the victim’s father had built, could plausibly be challenged as doctored, and a jury might have wondered.

If the concealed backup had been the only evidence, the case would have been a fight.

But Lars and Sigrid could not leave the visible camera alone.

Their guilt made them tamper: they had to get rid of the obvious device above the pantry, had to throw it away, had to be seen on the garage recording cutting into the hidden one.

And in trying to erase the evidence, they created more of it — a discarded camera whose internal clock, matched against the backup and the hospital’s dispatch logs, proved that both recordings were exactly what they claimed to be.

You cannot fake two independent devices into agreeing to the second; the only way they agree is if they both recorded the same real events at the same real time.