German Male Nurse Serial Killer of At Least 90
Niels Hoegel. I can find absolutely nothing about his personal life - the total opposite of what would be the case of any straight serial killer - so you know what that almost certainly means.
"First: Do No Good." - The Hymiecratic Oath
"The man who does not exercise the first law of nature—that of self preservation — is not worthy of living and breathing the breath of life." - John Wesley Hardin