Note 4 — Chapter XI · EUTHYPHRON.
Reading edition
According to the Attic law every citizen was bound, in case any one of his relatives (μέχρις ἀνεψιαδῶν) or any member of his household (οἰκέτης) had been put to death, to come forward as prosecutor and indict the murderer. This was binding upon the citizen alike in law and in religion.
Demosthen. cont. Euerg. et Mnesibul. p. 1161. Jul. Pollux, viii. 118.
Euthyphron would thus have been considered as acting with propriety, if the person indicted had been a stranger.