"I was just in utter shock and disbelief. I felt like it was just a bad dream, that I was going to wake up and none of this was true," his former co-worker Melanie Duke told ABC11 via picture phone from the western Kentucky town.
She says she agreed to talk to ABC11 because she wanted to vouch for Phelps' character.
The psychiatric nurse says she knows the 28-year-old bible college grad as a man of God whom she allowed to babysit her children.
But she found the 911 call Phelps made early Friday morning "chilling."
Listen to the chilling moment Matthew Phelps calls 911:
"At the beginning, he's very a, he's exhibiting disassociation," she said.
Early on, Phelps told a 911 dispatcher, "I had a dream and then I turned on the lights and she's dead on the floor. I have blood all over me and there's a bloody knife on the bed and I think I did it."
But Duke noticed a distinct change near the end of the call saying, "As the call progressed he started realizing what had happened and then was in that state of shock and just utter disbelief."
That's when you hear Phelps sobbing and telling the 911 dispatcher, "She didn't deserve this. Why?"
Phelps also told the dispatcher he had taken too much of a cold medicine that contains an ingredient experts say can cause hallucinations.
And Duke thinks that is at the heart of the crime.
"He was not cognizant at the time that this happened. I know Matt well enough to believe that with all my heart, that Matt did not do this intentionally," she said.
But, as a mother, Duke says she can't help but think about what the family of 29-year-old Lauren Phelps is going through.
"I can't imagine. I mean I have two children, a daughter and a boy, a son. And I'm very saddened over what they are having to go through, this tragedy. So I do want to send them my condolences and my prayers," Duke said as she choked back tears.
Duke knows there is another side to this story but until Lauren Phelps' family and friends speak out we will have to depend on the justice system to provide more facts about the state of the couple's nine-month marriage.
In the meantime, Duke says she thinks of 28-year-old Matthew Phelps as the only man outside her family she allowed to babysit her young daughter and son.
"That's how much that I trusted Matt and the type of man, and I still trust, it's not trusted past tense. I still trust Matt today and I would let him around my kids today," she said.