She pounded fruitlessly for 10 minutes on the door of the Kansas City, Missouri, rental belonging to Jordan Willis, where McGeeney and his friends were last seen two days earlier.

Then she broke in through a basement window, yelling to see if there was anyone in the house, a relative told The Post.

Next she walked upstairs, looked out the large back windows and saw a grisly tableau on the snow-covered patio.

Mahoney first spotted the frozen body of one man, David Harrington, seated upright in a lawn chair.

She was so upset that she did not immediately see that her fiancee was also dead on the ground, beside a third man, Ricky Johnson, who was also dead.

“April saw David and she totally panicked and almost couldn’t breathe and she called the police,” Clayton’s uncle, Jim McGeeney told The Post.

“The cops showed up within minutes and Jordan opens the door no problem, wearing his boxers and holding an empty wine glass.”

Since then, the mystery of how McGeeney, 36, Harrington, 37, and Johnson, 38, died seemingly simultaneously in the snowy backyard while Willis, their host, a 38-year-old HIV research scientist, said he had been sleeping for 48 hours and had no idea his buddies had expired in full view of the house, has only deepened.

The temperature in the backyard in the early morning hours of January 8 when the men died was just about freezing.

Preliminary toxicological results Thursday indicated the men died from the effects of cocaine and fentanyl.

The toxicological reports were not publicly released by Kansas City Police, but some bereaved relatives were briefed on their contents, a family member told The Post.

Two family members told News Nation that the bodies contained three times the amount of fentanyl needed to kill someone.

But friends and family of the dead men say many questions are still unanswered, especially about Willis. More than one person said it sounded like the “Breaking Bad” TV series come to life.

Willis has a PhD from Vanderbilt University. As an HIV vaccine researcher, he worked both at the International AIDS Vaccine Initiative’s Neutralising Antibody Center in La Jolla, California, and from his native Kansas City.

His academic resume includes 55 published papers — five times the academic output of ex-Harvard president Claudine Gay — and an award from the Scripps Consortium for HIV/AIDS for his contribution to the development of an HIV vaccine.

But his dead friends — they all met at Park Hill High School, a mile away — had more blue-collar jobs: McGeeney worked construction and Harrington was a flooring contractor.

Some friends and family members have commented to each other and the media that Willis might have cooked up something extra in the drugs the men took that night. A source close to the family disputed that, speaking to Fox News Digital.

Willis was arrested and charged with a misdemeanour DUI in 2011 in Tennessee, according to public records — hardly the mark of a Midwestern Walter White — and has no further criminal record.

“The mad scientist agenda is absolutely ridiculous,” the source said. “The fact that he is a scientist is irrelevant.”

But not everyone is convinced.

“A bunch of people reached out to Clayton’s sister and told her that Willis had been known as ‘The Chemist’ in high school,” Jim McGeeney told The Post.

“They said he would go to parties and make people feel good with the drugs he enhanced. I don’t know if he concocted something or not that night. The police won’t tell us anything.”

April, he said, is “all tore up. She barely wants to talk. The funeral for Clayton was very tough. They were together for years and had a great life.”

Willis, the three dead men and a fifth friend gathered at the four-bedroom rental in the suburban Northland sprawl 20 minutes north of downtown Kansas City, some time after the Chiefs defeated the Los Angeles Chargers at SoFi Stadium 13-12 in the early evening of January 7.

The fifth man, Alex-Lee Weamer, arrived at the home around 7pm and told the police when he left at 12.01am all the men were up and watching a re-run of “Jeopardy!”

Willis, whose stories have changed slightly when recounted by his lawyer, John Picerno, claims he went to sleep around 12.30am, when his friends were still there. At one point it was claimed he saw them leave. Picerno did not respond to repeated requests for comment from The Post.

Early on the morning of January 9, both Mahoney and Johnson’s mom Norma Chester texted Weamer-Lee asking where the men were. Weamer-Lee then texted Willis both on his phone and via Facebook but he apparently never answered.

That night at about 7pm, a close friend of the men, Dakota LaTier, pounded on Willis’ door for about 20 minutes with no response.

Then Mahoney came by two hours later, saw two vehicles belonging to the deceased out front — and knocked on the door herself before breaking in the tiny basement window, getting access to the backyard and making her deadly discovery.

She called the police, who arrived 10 minutes later. This time, Willis answered the door right away. He was handcuffed briefly but released without charge; cops said there was no evidence of foul play.

Michael Baden, the former chief medical examiner for New York City, who has investigated numerous high-profile deaths, told The Post that it would be unlikely for three people taking drugs to die at the same time “but it wouldn’t be unusual for three people to pass out at the same time.”

“They usually pass out and sleep it off but if you pass out in the snow and cold the body temperature falls so quickly that often people are dead within an hour,” Baden said.

On January 20, Willis’ defence lawyer John Picerno sent out a press releaseEditSign saying Willis was “unaware” that his friends had died and that he had been asleep with “earbuds” and a “fan.”

Picerno did not answer more than a dozen calls from The Post. Willis has checked into rehab, according to a report.

Willis is “facing his addiction head-on,” a source close to the family told Fox News Digital, calling the deaths of his friends an “enormous wakeup call.”

“After the shocking loss of three of his close friends under extremely tragic circumstances, Jordan recognised that he had a problem with addiction,” the source said, without elaborating on the exact nature.

“He immediately checked himself into rehab after vacating his home and putting his things into storage.”

Jim McGeeney said that Willis moved out of the rental, which is reportedly owned by his parents, the day after the bodies were found. His beloved rescue pit bulls, Daisy and Sadie, may have been with his parents all the time.

“I don’t know about him but these guys (the deceased) were not junkies,” he said. “They weren’t drug addicts with needle marks in their arms.

“They were professional people and if they were doing cocaine recreationally, they never expected it to be laced with fentanyl and lethal.”

Fentanyl has killed more than 850 people in the nine-county Kansas City area since 2018, the Kansas City Star reported late last year.

Jim McGeeney pointed out that on January 8, as the dead men apparently lay frozen in the backyard, a 38-year-old Kansas City man and his 31-year-old partner were arrested on charges of drug trafficking.

Cops found more than 105 grams of fentanyl — enough to kill 52,000 people — along with supplies used to package and distribute the drugs in their suburban home, according to the news release.

“It’s so sad,” McGeeney said. “I wish people knew that if they’re going to use drugs like this they would at least buy one of those test kits to see if cocaine has been laced with fentanyl.

“Three families have been ripped apart forever over this.”

— This story originally appeared on nypost.com and has been republished with permisson