Snopes acknowledges that cats could “upon extremely rare instances accidentally cause a death” by smothering, but cats do not do it “with malice aforethought.”
If the avenger of blood comes in pursuit, the elders must not surrender the fugitive, because the fugitive killed their neighbor unintentionally and without malice aforethought.
Otherwise, the avenger of blood might pursue him in a rage, overtake him if the distance is too great, and kill him even though he is not deserving of death, since he did it to his neighbor without malice aforethought.