He then said that he had taken too much Coricidin, a cold medication targeted at people with high blood pressure.
“I took, I took more medicine than I should have,” he said. “I took Coricidin ... because I know it can make you feel good, so a lot of times I can’t sleep at night so I took some.”
“There’s so much blood,” he said, his voice breaking.
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“She didn’t deserve this,” he sobbed. “Why?”
Raleigh police said in a statement that officers were dispatched to the home around 1:15 a.m. on Friday in response to a report of a stabbing and Phelps was taken into custody without incident.
Phelps had his first court appearance on Tuesday in Wake County court, where a judge ordered him held without bond. Phelps did not enter a plea.
The judge also said Phelps could face the death penalty.
"You can receive death or life in prison without the possibility of parole," Wake County District Court Judge Keith Gregory said.
Phelps’ next court appearance was set for Sept. 25.
Phelps' attorney, Joe Cheshire, offered his condolences to the victim's family outside court on Tuesday afternoon, and asked the public to "withhold judgment in this particular case until we know more."
"There's a lot to this story that I believe will be told in the future," he said.
Bayer, the pharmaceuticals giant that makes Coricidin, said in a statement that the company "extends our deepest sympathies to this family."
"Patient safety is our top priority, and we continually monitor adverse events regarding all of our products," Bayer said. "There is no evidence to suggest that Coricidin is associated with violent behavior."
But some of the known side effects of Coricidin range from racing heart and drowsiness to a drunken feeling and hallucinations.
And, in a 2012 study, scientists concluded that high doses of a specific ingredient in the medicine have been found to cause mania and hallucinations and that potentially left people “at risk for violent and self-destructive acts.”
It’s not the first time a cold medicine has been alleged to have led to a killing.