[1] A lieutenant in the Los Angeles Police Department (LAPD), Decker is assisted in solving crimes by his Orthodox Jewish wife Rina Lazarus.
When he meets Rina, a young widow, during an investigation at a yeshiva in The Ritual Bath, he is compelled to explore the religion for himself, and eventually became a religiously observant Orthodox Jew.
To his police colleagues, he remains "Peter", "Loo", "Rabbi", or "Old Man", but at moments of special intimacy and tenderness, Rina calls him "Akivale".
For example, the plot of Stone Kiss is launched by a call from his Jewish half-brother Jonathan - a rabbi in New York, with whom Decker shares a biological mother, but whom he met only in adulthood; the plot later also involves his Christian step-brother Randy, a policeman like himself residing in Florida.
[1] Unsurprisingly, Decker feels more comfortable with Randy - with whom he shares childhood experiences, though no biological relation.