Sheila was half medicated with one worry after the other compounding her distress Jane!
Either she carried out the murders in the grip of a psychotic episode or a bout of severe clinical depression.
Who knows?
Her Haloperidol dosage was reduced from 200mg to 100mg.
Sheila had 15 ng/mL of haloperidol in her blood at the time of her death.
According to a 1992 study "Haloperidol Blood Levels and Clinical Effects" They consider Haloperidol blood levels as follows -
low (2 to 13 ng/mL), medium (13.1 to 24 ng/mL), or high (24.1 to 35 ng/mL).
According to a 1980s study, heavy sedation is associated with levels in excess of 50ng/mL