Holly Eudy was in a 10-year relationship with successful real estate agent, Todd Kohlhepp, before he was arrested in November last year.
The arrest followed the discovery of a woman, Kala Brown, 30, who had been held captive with chains and raped daily in a shipping container on Kohlhepp's property for two months.
Kala told police Kohlhepp had shot her boyfriend, Charlie Carver, in front of her when they'd first arrived at the property after answering an ad for work. A search uncovered Charlie's body, as well as several others.
In May, Kohlhepp pleaded guilty to the murder of seven over a 13-year period, and was sentenced to seven consecutive life sentences with no possibility of parole.
Now, Ms Eudy has spoken of her relationship with the murderer. When she met him in 2006, he had already killed four people.
'He gave me a lot of attention, made me feel like I was important,' she told Inside Edition.
'I knew there was something that didn’t sit right with me about him, but I couldn’t really put my finger on it.'
Ms Eudy later learned that Kohlhepp had used money she'd loaned him to buy the storage container he used to lock up Ms Brown. He'd told her that he needed it to store supplies.
Ms Eudy said she wasn't suspicious – even after visiting it, finding only cans and water.
She only realised what sort of danger she was in when Kala Brown was filmed being transported to hospital after her rescue. She could be heard telling authorities that Kohlhepp had more crimes up his sleeve. 'Some girl named Holly, he’s supposedly planning to kill,' she was heard saying.