闷死

The smoke and fumes almost suffocated me.

烟雾差点儿把我闷死。

The killer smothered the victim with a pillow.

犯用枕头闷死受害者。

The baby suffocated under its pillow.

婴儿闷死在枕头下。

You were strangled to death with a plastic sack. It's probably an odd thing to hear - I wasn't sure how to sugarcoat it.

你确实被个塑料袋套上给闷死。可能听着挺怪的，我不晓得怎么说才能好听点。