In the novel The Moving Finger, Richard Symmington is the solicitor in Lymstock. He is living along with his wife Mona Symmington, his stepdaughter Megan Hunter, his two sons and the nursery governess Elsie Holland in a big house. Richard Symmington is described as intelligent, but ruthless by Miss Marple.
He is described as "the acme of calm respectability, the sort of man who would never give his wife a moment's anxiety". He has a "long neck with a pronounced Adam's apple, a slightly cadaverous face and a long thin nose".
Richard receives an anonymous letter alleging that he is having an affair with his lady clerk, Miss Ginch. He takes it to the police.
After the apparent suicide of his wife, he is very dazed and bewildered. His wife had received an anonymous letter alleging that Colin was not his child. At the inquest, Richard testified that this was not true.
Richard has known Dr Griffith and his sister, Aimée Griffith, for a long time, as he used to come and stay in their part of the country when Dr Griffith had a practice "up north". Aimée says that he is a proud man, and very reserved, but could be very jealous. Aimée is in love with him, but he is unaware of this until much later in the novel.
The police find out that the typewriter used to type the envelopes for the anonymous letters was an old one that Richard had donated to the Women's Institute. the envelopes were all typed using one finger.
Megan approaches Richard, and tells him that she wants money from him, or she will tell what she saw him doing to her mother's medication on the day she died. Richard writes her a cheque, and later drugs her, and attempts to kill her by putting her head inside the gas oven. He is caught by the police, who are lying in wait for him.
It is revealed that Richard killed his wife because he was in love with Elsie Holland. He wanted to marry her, but also wanted to keep his respectability, his house, and his children.
He wrote the anonymous letters to create a death that seemed incidental to something else, because he knew that suspicion often falls on a husband when a wife dies unexpectedly. He typed all the envelopes before giving the typewriter to the Women's Institute, and composed the letters based on letters from past cases that he had heard about.
On the day of his wife's death, he put cyanide in the top cachet of the ones she took in the afternoon. Then he added a little cyanide into the glass of water she had used to swallow the cachet, threw the anonymous letter into the fireplace, and put the note saying, 'I can't go on' near her body. It was in her own handwriting, and Miss Marple suggested that he had found a message she had written on a telephone pad, and had torn off the part that would be useful to him.
He also killed Agnes Woddell, because she had been at home on the day Mrs Symmington died, and had therefore known that no postman had come to the house, and yet Mrs Symmington had apparently received an anonymous letter.