Kalliel was an Abhorsen. According to Mogget in Abhorsen, he was the twelfth Abhorsen. He reportedly mistrusted Mogget and kept him locked up for much of his time as Abhorsen. Kalliel's disappearance had been a mystery to Mogget until what would appear to be his remains were discovered by Lirael, Sameth, Mogget, and the Disreputable Dog in the tunnels under the Abhorsen's House. It is therefore assumed that Kalliel was responsible for digging the well in the rose garden, and that his successor covered and locked the well.
 Abhorsen by Garth Nix, p35 (London: HarperCollins)