Mercy killing (not assisted suicide) and the ramifications of the karmic action

Of course one of the 4 imponderables is the results of karma. I am just asking if there is any sutta explanation on the effect of killing with malice compared to mercy killing? Difference between mercy killing and assisted suicide: Assisted suicide is what it is, killing someone after they ask you to assist their suicide. Mercy killing is killing others out of mercy. For eg if you see an animal in extreme pain who is dying of whatever illness or blood loss, they cannot actually ask you to kill them for themselves so one is killing the other person out of mercy to alleviate their suffering. Or if you were on a battlefield and an enemies legs and limbs are blown to pieces so they cannot harm you any more and are no longer a threat but are in vast amount of suffering and pain so you kill them out of mercy.