In which work of 1930 did the character Miss Marple appear for the first time in a full-length novel?

The Murder at the Vicarage is a work of detective fiction by British writer Agatha Christie, first published in the UK by the Collins Crime Club in October 1930 and in the US by Dodd, Mead and Company later in the same year. The UK edition retailed at seven shillings and sixpence (7/6) and the US edition at $2.00.

It is the first novel to feature the character of Miss Marple, although the character had previously appeared in short stories published in The Royal Magazine and The Story-Teller Magazine, starting in December 1927. These earlier stories would later appear in book form in The Thirteen Problems in 1932.