Killer? I dare say, but perhaps more of an outlaw;as in Josey Wales.
As they are both pursued by Red Legs...
"Please do not be tempted to transfer the spawn of Common Frogs to garden ponds. There is a risk that in doing so you may spread the disease redleg, that is currently afflicting this species in the UK. Frogs will very quickly find and use your garden pond of their own accord, if conditions are favourable to them."
Ignorance is bliss, bliss is happiness, I am happy...to draw your attention to the possible connectivity in the foregoing.