has an idea that has crossed my mind too: Make the penalty for such crimes utter anonymity.
Thou hast rebuked the nations, thou hast destroyed the wicked; thou hast blotted out their name for ever and ever. The enemy have vanished in everlasting ruins; their cities thou hast rooted out; the very memory of them has perished. But the LORD sits enthroned for ever, he has established his throne for judgment; and he judges the world with righteousness, he judges the peoples with equity. – Ps 9:5-8
The only response to this is prayer and penance–and cultivation of a culture that does not glorify violence as a quick ticket to fame.