Flora killed several thousands

Question: Flora killed several thousands of people without mercy. Afterwords, Flora disappeared and was never seen again. Yet the police never pursued her.Why?

Question: What do you call a sad bird?

Question: What can be broken but never forgotten?

Question: Where do all the letters sleep?

Question: People see through me, but none pass through without killing me. I can be anywhere, and can be seen double or single. What am I?

Question: What tastes better than it smells?