The twins were found 200km from their Colorado home, in the Denver suburb of Broomfield.
In 2016, the Eldritch sisters had appeared on a TV show about their surgery — more commonly used to treat Parkinson's Disease — at Denver's Littleton Adventist Hospital.
Last year they appeared on an episode of The Doctors talking about their co-dependency and deep fears at the possibility of separation.
In TV interviews the Eldritch sisters revealed that as toddlers they were obsessed with tucking in their shirts, frequently washing their hands and wearing socks with no wrinkles.
As they became adolescents, the cleanliness obsession grew worse; they could go through a bottle of shampoo in one shower session.
Because of the anxiety about lengthy showers, sometimes they didn't bathe for up to two weeks.
They used multiple bottles of rubbing alcohol and hand cleanser, wore latex gloves, cleaned their bathroom up to three times a day and could not use public toilets.
Every speck of lint had to be removed from their clothing and they couldn't walk barefoot, even at home.
After trying to take their own lives at the age of 16 they were diagnosed with OCD.
Over the next 15 years, they tried medication, counselling and therapy to cope with their shared affliction.
Neurosurgeon David VanSickle agreed to perform the deep brain stimulation surgery on the twins in the hope of bringing them relief.
Electrode wires were placed on areas of their brain and connected to battery packs implanted in their chests.
The aim was "inhibiting the part of the brain that's overactive" by regulating the amount of stimulation and suppressing anxiety.
Their specialist reported that within a year after the surgery, the twins' mental health had improved and they were "finding hope and joy in simple things."
Detectives in Fremont County, Colorado are conducting further investigations into the sisters' deaths.
WHERE TO GET HELP:
If you are worried about your or someone else's mental health, the best place to get help is your GP or local mental health provider. However, if you or someone else is in danger or endangering others, call police immediately on 111.
OR IF YOU NEED TO TALK TO SOMEONE ELSE:
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