04/28/2014 at 07:00 PM EDT
There is only one person to blame for accused Craigslist killer
– and wannabe serial killer – Miranda Barbour's lies and violent behavior, her sister told Dr. Phil McGraw in an episode of his show that aired Monday
"My mom made Miranda the way she is," Ashley Dean
said as their mother, Elizabeth Dean, dissolved into tears. "My mom has been a bad mom."
Ashley went on to say that their mother was inattentive, had numerous men over that she just met after divorcing their father and even left her to babysit Miranda when she was 6 and Miranda was 3 years old.
"I just want to make it clear that it's not my sister's fault," she said. "She's not this monster on her own. It's come from someone else."
Elizabeth said she took Miranda to many therapists over the years to get her the help she needed.
"I love Miranda," she said. "I will never turn my back on her. She's my daughter."
Barbour, 19, and her husband, Elytte, have been charged with
the Nov. 11 murder of Troy LeFerrara, 42, whom they allegedly met via a Craigslist ad and lured to his death. They have both pleaded not guilty.
In February, Miranda told a Pennsylvania newspaper reporter she killed at least 21 other people
. While Ashley and their mother believe Miranda killed LeFerrara, they do not believe she killed anyone else.
"My daughter is not a serial killer," Elizabeth Dean told McGraw. "I don't believe Miranda has killed more than one person because this one is so sloppy."
Neither does McGraw, who read Miranda's journal dating back to May 8, 2010, which Elizabeth Dean says she found earlier this year.
"Nowhere in there is there one word, one syllable, one even veiled reference to having killed anyone," McGraw said. "It seems to me, given the candor of some of these entries, that would be an odd thing to leave out."
McGraw also read an email his show received from Miranda on Nov. 10, 2012, pleading for help for her mother, whom she called a "pill-popping drunk."
"She's so verbally abusive and it hurts so much," the email said. "If things keep going the way they are she's going to kill herself ... I don't know how to help her."
Elizabeth says she was taking medication for a medical condition and was drinking at the time.
"I was very depressed," she said.
McGraw said his show reached out to Miranda after receiving the email but was not able to make contact with her.
Ashley said similar things about their mother and added that she and her sister were both sexually assaulted by an uncle when she was 6 and Miranda was 3. He went to prison for nine years.
"You have to understand where Miranda's coming from," Ashley explained. "You have to understand what happened to her when she was younger."
Both Miranda and her husband face the death penalty. Though Ashley feels Miranda participated only to please her husband, she refuses to take her phone calls from prison and believes she deserves the death penalty if convicted.
"I believe she deserves the consequences of her actions," she said. "Do I want to see her die? No."