Children often eat in their own homes. DNA in 3 places on the dead victim trumps food eaten by a child in their own home.
I had a stalker for 12 years who came into my home whenever he pleased and left notes inside my closets and drawers after stealing whatever he wanted. It was a cop. It happens. Criminals do whatever they want whenever they want. Don't rule out the possibility that the killer may have led the little girl down to eat pineapple.
Don't rule out he brought pineapple with him. Nutty people do nutty things. Anyone bold enough to commit this crime or my cop/stalker for 12 yrs no less has easy access to anyone at will in the community. You know, like BTK did for decades undetected.
10's of thousands of people in the US process data from your medical records, bank records, places of employment, loans, applications and what sweatshirt you bought on sale in the year 2000 at wal mart. Cops and utility company workers have access to your personal information. Bank employees. Vehicle registration forms, auto dealers. Many people you would never think of know everything about your life, your identity, your bank acct. numbers, when you had your last medical exam and the results of it. It is ALL data processing. People order new checks for regularly, but never give a thought to who has access to that intimate details of their lives. They believe it's somehow secret. It's not. a lot of people have access to those things. Some take documents home with them even though they're not supposed to. Some take stacks of info and pitch it into dumpsters so they won't have to do the work required to process it. There for any bum on the street to have. Phone company workers, the man at the hardware store who made your new keys. It's all computerized and logged in. All he has to do is make as many duplicates as he wants.
When I had my stalker we wracked our brains trying to think who could have such free access to our lives. Calling us up periodically catching us off guard. Telling us everything about our lives and what he was going to do with it. He knew everything about us while we knew nothing about him.
If you don't think that can happen, thank your lucky stars. It happens to many people. It happened to me. We hear of ID theft regularly, yet you refuse to accept the reality that it's possible someone could have gained access to these people's finances and written that note.
You seem to be conveniently leaving out life and what possibilities exist to plague anyone anytime anywhere.
Nothing better can befall a man than to be born lucky - Mark Twain