The affix ṇini comes after the verb han 'to kill' with the sense of past time, when the word in composition is in the Accusative -2nd case.,
As पितृव्यघातिन् 'who has killed his paternal uncle'; मातुलघातिन् 'who has killed his maternal uncle'; हन् + णिनि = घन् + णिनि 7.3.54 = घत् + णिनि 7.3.32 = घातिन् 7.2.116.
This affix is employed only when censure is implied. Therefore it is not employed in चोरं हतवान् 'he has killed the thief'.
The anuvritti of the word कर्मणि of this aphorism extends up to sutra 3.2.96.,