@Oblomov18
I disagree that leaving a 4 year old for an hour is somehow wrong. Children start school at 4. The year they are 5, thus they start aged 4. I could leave mine happily playing, pre school. For an hour. As I pottered around.
Some children need more supervision than others depending on their personality and needs.
But if you never leave yours unsupervised, then you probably aren't preparing them for school properly.
WOW. You HAVE to be KIDDING? FFS 
She didn't leave the child alone for a bit. The FOUR YEAR OLD INFANT left the house, and she didn't even notice until the police brought the child back. Yes it IS disgusting, and appalling parenting. If you cannot see that and accept that, God help you.
Then again, reading all your posts on this thread, there is no WAY you are serious. You can't be. Your posts are bizarre.
So are the posts from a few others here. I cannot BELIEVE that people actually think what happened with the OP's friend is OK.
I bet in real life, they wouldn't say to people that they think it's OK.
Because they know it's not.