Missed getting into this book:
Angels of Death
https://www.walmart.com/ip/True-Crime-Casefiles-Angels-of-Death-Murderous-Medics-Nefarious-Nurses-and-Killer-Carers-Paperback-9781398820500/805676655?wmlspartner=wlpa&selectedSellerId=0&&adid=22222222227805676655_142373258550_17687600153&wl0=&wl1
I think the woman on the cover of that book is Canadian RN Elizabeth Wettlaufer, who killed 8 and injured 6 over a span of nine years.