This root form (lemma) is used in 2 different forms in the NT: ἐπνίγοντο (IIP3··P), ἔπνιγεν (IIA3··S).
It is glossed in 2 different ways: ‘he was strangling him’, ‘they were_being drowned’.
OET MARK 5:13 Greek word=ἐπνίγοντο (epnigonto) Morphology=IIP3··P English gloss=‘they were_being drowned’ SR GNT MARK 5:13 word 40
OET MAT 18:28 Greek word=ἔπνιγεν (epnigen) Morphology=IIA3··S English gloss=‘he was strangling him’ SR GNT MAT 18:28 word 20