Agreed
Whether watching the cells to prevent problems or as a reliable recorder of events.
IMHO:
It's just that they seem to malfunction during these types of incidents.
To be fair though, its possible she was arrested while abusing something which killed her, or she was injured prior, but the cops are still responsible for stowing a person of diminished capacity.
She was recently separated, possibly lost her kids, and also may have fit the profile of someone who might be suicidal. It would be ironic and sad if the cops jailed her to protect her from herself.
The kids also have to grow up with " mum died in jail".