Born in 1962, Irene Leidolf was a nurse's aide at the Geriatriezentrum am Wienerwald in Lainz, Vienna. She was married but reportedly spent more time with her colleagues than at home. Leidolf was known to be impressionable and was drawn into Wagner's circle, eventually participating in the murders.

Leidolf became an active participant in the group's killing spree, assisting in the administration of lethal doses and the drowning method. She was convicted in 1991 for five murders and received a life sentence. Leidolf was released from prison in 2008 due to good behavior.​