A disgruntled coworker named Steyn provides the seashell that implicates the central character in his disgraceful crime when his mistress places it in his pocket.  
At its beginning, the narrator laments, "Perhaps I could have saved him, with only a word, two words, out of my mouth."  The protagonist's father Jakob only reads the Bible, but the protagonist audaciously gives him a bird field guide for his birthday, and the two go on a birdwatching walk while picnicking.  A disgruntled coworker named Steyn provides the seashell that implicates the central character in his disgraceful crime when his mistress places it in his pocket.  The protagonist gives his diary to his wife Nella after he is imprisoned under the Immorality Act for his affair with a black woman named Stephanie.  FTP, name this work featuring policeman Pieter van Vlaanderen, the second novel of Alan Paton.
At its beginning, the narrator laments, "Perhaps I could have saved him, with only a word, two words, out of my mouth."  
{Too Late the Phalarope} or {Liian myöhään vesipääsky} (5) [AH]