But there was yet another blatant warning sign. Three days after the Jenkins' death, Serene Solinski hosted a birthday pool party and sleepover for her 13-year-old daughter, Levi Rawl, and her eight friends at the hotel. When they checked into Room 325, the hotel room located above Room 225, Solinski said the girls became very ill.
"All girls were very sick, puking in bathtubs, sinks, toilets while I'm calling their parents, they were falling off like flies," Solinski said. "And it was pretty scary."
According to Solinski, all but one friend went home with their parents that night, too sick to continue celebrating. She said she alerted the front desk, and "my name was written on a yellow sticky note and I was told the general manager would be told."
Mallatere denies ever being told of Solinski's stay by his staff.
After Jeffrey Williams was found dead, state investigators discovered that the hotel pool heater's exhaust pipe was damaged. In investigation photos obtained by ABC News, the pipe can be seen full of holes and propped up with a VHS cassette tape and a hotel ice bucket. Investigators say the exhaust pipe was leaking lethal levels of carbon monoxide from its location in the drop ceiling just below Room 225.
Mallatare said he had no knowledge of the damaged pipe until the state's investigation.
"We never would've re-opened that room if we had any thoughts whatsoever that there was something wrong or that that would hurt somebody," Mallatare said.
North Carolina Department of Health and Human Services (DHHS) told ABC News the medical examiner had received Shirley Jenkins' toxicology report on June 3, 2013, showing she had been killed by carbon monoxide poisoning -- four days before Jeffrey Williams died.
In a statement to ABC News, DHHS spokesperson Kevin Howell wrote, "Hall did not request that the toxicology analysis be expedited."
Hall resigned from his state-appointed post in June. He didn't respond to repeated attempts to contact him.
On Jan. 8, a North Carolina grand jury indicted Mallatare on three counts of involuntary manslaughter and aggravated assault for Jeannie Williams' injuries. After turning himself in on Feb. 10, Mallatare entered a not guilty plea and posting a bond of $40,000. He faces an arraignment hearing on Feb. 17.
Unlike smoke detectors, there is no federal requirement for carbon monoxide detectors in hotel rooms. A handful of states, now including North Carolina, do require them in some areas of the hotel.
When asked if she thought her son would still be alive if the Blue Ridge Plaza Best Western had carbon monoxide detectors installed, she said, "That's my understanding."
The Williams family hopes to start a foundation to raise awareness of the need for carbon monoxide detectors.
"One thing that we would like is for more hotels or state laws, if they would put carbon monoxide detectors in hotels," Jeannie Williams said. "If you walk into a hotel room, don't assume that everybody there is doing everything they can for your safety. As travelers, maybe we need to take more control of that for ourselves by traveling with CO detectors."
In raising awareness of the horrors she faced in Room 225, she hopes to spare another family the pain she now carries.
"One thing I'll never have… I won't have the mother and the groom dance," Williams said. "But I just take it one step at a time, and I just know I'll see him and I'll dance with him in heaven one day."