The North Carolina Bible college graduate who said he had taken too much cold medicine the night his wife was fatally stabbed pleaded guilty to first-degree murder Friday.

Matthew Phelps, 29, an aspiring preacher, called 911 on Sept. 1, 2017, and told authorities he believed he may have killed his wife, Lauren Hugelmaier Phelps, 29. She was found with 123 stab and cut wounds on her body. The couple had been married for less than a year.

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"I think I killed my...there's blood all over me...and there's a bloody knife on the bed. I think I did it," Phelps said in the phone call, adding he had taken too much Coricidin Cough and Cold.

On Friday, a blood test showed cough medicine in Phelps’ body but “not a toxic amount that would cause dizziness or hallucinations,” prosecutors argued, according to The News & Observer. Prosecutors also said Friday that Phelps was violent toward his first wife and allegedly dragged her by the hair through a hallway. The two divorced following the alleged incident.

Phelps began his relationship with his future wife, who he knew from middle school, when he contacted her through Instagram. Friends of Phelps told detectives the couple often argued and were experiencing financial trouble, court documents stated. Search warrants also showed Phelps was obsessed with the main character of the movie "American Psycho."

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"It was learned that Matthew Phelps was obsessed with the movie 'American Psycho' and this Instagram account shows numerous photographs of scenes from the movie and Phelps dressed as the main character," a detective wrote in documents filed with the Wake County Magistrate's Office. "The movie is about a serial killer, and Phelps expressed interest to a friend regarding what it would be like to kill someone."

Phelps will serve life in prison without the possibility for parole as part of the plea.

“He’s pleading to spend life in prison to avoid the possibility of death,” Phelps' attorney, Elliot Abrams, told The News & Observer.

Fox News’ Nicole Darrah contributed to this report.