Photobiological effects at Earth's surface following a 50 pc Supernova
Recent paper on arXiv describing the likely effects of local supernovae, such as are thought to have happened ~2.5 and 8 Mya.
Short version: not enough damage to cause a major extinction event, much less "sterilization." So, we're left with the most likely cause for Lucifer-3 being some flavor of gamma ray burst.