Matthew Phelps told 911 that he took too much cold medicine before waking up to find his wife dead

Matthew Phelps sounded detached — and then progressively more distraught — when he called 911 in the early hours of Sept. 1 to say that his wife, Lauren Hugelmaier Phelps, had died.

“I had a dream and then I turned on the lights and she’s dead on the floor,” he said in the call, audio of which was obtained by PEOPLE.

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He then described a grim scene: “I have blood all over me and there’s a bloody knife on the bed and I think I did it. I can’t believe this.”

In his version of events, captured in that conversation with the dispatcher, Phelps had gone to sleep the night before, after taking too much cold medicine, and then woke up after midnight to find Lauren fatally stabbed in their two-bedroom townhouse in Raleigh, North Carolina.

Before breaking down into audible sobs, the 28-year-old aspiring pastor explained why he believed he couldn’t recall what had happened.

“I took more medicine than I should have,” he told 911. “I took Coricidin Cough & Cold because I know it can make you feel good. A lot of times I can’t sleep at night. So, I took some.”

Authorities arrived soon after Phelps’ call to find Lauren’s body as he said. He was arrested later that same day and charged with first-degree murder in connection with the death of his wife, a 29-year-old Sunday school teacher whom he married less than a year ago.

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Image zoom From left: Lauren Hugelmaier Phelps and Matthew Phelps Facebook

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Although police have released few details about the headline-making case, investigators have expressed doubt about Phelps’ account of the stabbing, saying in a statement that “preliminary findings have established that the crime was not a random act.”

Phelps, who studied evangelism at Kentucky’s Clear Creek Baptist College, has pleaded not guilty and is being held without bail at the Wake County Detention Center in North Carolina. As the story continues to garner national attention, Phelps’ attorney is urging the public to avoid jumping to conclusions.

“It’s a very tragic situation,” Joseph Cheshire said in a statement to PEOPLE. “There’s a lot to this story I believe will be told in the future.”

It remains unclear how much Coricidin — if any — might have been in Phelps’ body at the time he allegedly murdered his wife or whether he will try to use his self-proclaimed overdose as a defense. Still, the story has stirred discussion among toxicologists and some in the legal community.

RELATED VIDEO: Aspiring Pastor Accused of Killing Wife in His Sleep Blames Cold Medicine: ‘I Can’t Believe I Did This’

One criminal attorney told PEOPLE that a claim about the effects of cold medicine could be viable in court.

“It sounds farfetched to the general public,” said Chris Beechler, of Beechler Tomberlin in Winston-Salem, North Carolina. “But I will tell you, the idea that certain meds can get into your system and cause you to do things that you’re not aware of is completely possible.”

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Beechler, who is unconnected to the case, explained that “in North Carolina, if a jury finds that a person did these things while unconscious … the defendant would have to be found not guilty of the crime.”

Some experts say that abusing Coricidin can induce unpredictable and dangerous side effects similar to those associated with the street drug PCP — however, one toxicologist noted he’d “never seen a case like this, where someone commits murder under the influence of the drug.”

A spokesman for Bayer, the drug manufacturer that produces Coricidin, said, “there is no evidence to suggest” the drug “associated with violent behavior.”

“Patient safety is our top priority, and we continually monitor adverse events regarding all of our products,” the company said in a statement.

As officials work to solve the case, Lauren’s family works to come to terms with the death of the woman remembered as “sweet” and kind-hearted.

A family member told PEOPLE, “We’re just trying to deal with a lot of different emotions.”