Kristen Gilbert

Angel of death, sentenced to life in 2001.
Killed four by injecting them with a heart stimulant
(epinephrine/adrenaline).  Convicted on 3 counts of 
1st degree murder, 2 counts of 2nd degree murder, and
2 counts of attempted murder.

http://home.earthlink.net/~tomnvic/mass.html

http://www.crimelibrary.com/serial10/angels/8.htm