Sounds like a twisted Agatha Christie novel title doesn't it? It's not true that ThingOne's forst word was "murder". She's been saying simple words for a while, but she's not really said clear two-syllable words before (other than "dada", which isn't a real word). Before this week ThingOne has called both me and Anne (and most other people) Dada. Only this week has she started to realise that one of us is Dada and one is Mama. However, she's often not sure which is which.
She'll sit and point at one of us and say Mama and Dada until she gets it right and gets a reaction from us (we clap when she calls us the right name). But she gets a bit tied up and called us Mada, which comes out just like Murder (or rather, like Taggart saying Murder in a thick Scotch accent).
Let's hope this isn't a portent.