“I know my sister was strange, but never anything like this, no,” says Elizabeth.

TELL DR. PHIL YOUR STORY: Are you involved in a story that has made the headlines?

Her sister, Louise Turpin, along with her husband, David Turpin, is accused of starving, torturing and chaining their 13 kids to their beds. When the couple was arrested on January 14, 2018, police say what they found inside what some are calling the “California House of Horrors” was horrific. They said conditions in the house were deplorable and they claim that the children were only allowed to shower once a year, were not allowed to use the bathroom and were so malnourished they appeared to be years younger than their actual age.

Elizabeth says once Louise left home at 16 to be with David, she noticed what she calls her sister's strange behavior. Elizabeth claims Louise didn’t want to talk to her siblings or parents, and then in her 40s, she started to party like a teenager and bragged about having sex with a man other than her husband.

WATCH: Sister Of Louise Turpin Says: ‘I Always Thought She’d Be The Perfect Mom’

“She had blocked me and one of my other siblings off of Facebook,” Elizabeth says. “I haven’t talked to her on the phone for two years."

In the video above, hear more of what Elizabeth calls Louise’s “strange” behavior. And on Monday’s episode of Dr. Phil, hear from some of the Turpin’s former neighbors and what they say they saw. Check here to see where you can watch.

TELL DR. PHIL YOUR STORY: Have a story Dr. Phil won't believe?

The Latest In The Case Of Louise And David Turpin Accused Of Starving, Torturing And Chaining Their 13 Kids In So-Called "California House Of Horrors"