Panic grips the quiet American town of Moscow and the University of Idaho’s campus in mid-November 2022. The shocking news spreads swiftly: four students have been found deceased, savagely stabbed in a rental house on King Road.

Phones across the campus light up with urgent alerts from university authorities: ‘Police investigating homicide. Suspect is not known at this time. Stay away from the area and shelter in place.’ Helicopters circle above, while sniffer dogs scour the grounds.

However, the police adopt a different approach, asserting there is ‘no threat to the public’. This is a strategic decision by Chief of Police James Fry aimed at maintaining order. The police require calm to effectively gather witness testimonies and advance their investigation into this horrific crime.

In his bones, Fry knows that people are just as safe now as they were 24 hours ago. Common sense, and years of training and experience, tell him that when someone comes for you in your bed with a knife in the middle of the night, it’s personal. Whoever did this had a specific reason and is not likely to strike again randomly.

Teams of his officers are urgently building detailed profiles of the four victims. At least one of them was a target. Which one? Why? As yet, there is no handle on a motive. But the police don’t elaborate on this, instead they play things close to their chest, not making public what few clues they have for fear of alerting the killer and helping him cover his tracks.

They don’t reveal that a knife sheath was found next to one of the bodies and that it has gone to a laboratory for analysis.

But the lack of any information only fuels the panic. The local locksmith is overwhelmed as people who never felt the need to lock their doors in this sleepy little town are suddenly bolting themselves in.

The fact that everyone in Moscow (population 25,000) knows everyone else has morphed overnight from a source of pride and comfort to something scary. Neighbour suddenly mistrusts neighbour. Friend mistrusts friend. Customer mistrusts vendor. People are hiding from one another, the very connectivity between them all now toxic. Who knows who among them is the murderer? People are sleeping with their rifles under the bed.

Claire Qualls, a 21-year-old student who lives in a basement flat just two blocks from 1122 King Road, the murder house, has never wanted a gun, on principle. Now she plans to buy one and learn to shoot. Her dad is coming over to replace her cheap window that can easily be opened from the outside with a stronger one. She’s also going to get a personal safety alarm and keep it next to her at night. You simply pull it apart and it goes off. That way, she figures she’ll have a fighting chance if someone attacks her in her bed.

The rumour mill is now in overdrive, with stories that a Colombian drug cartel is involved in the murders. To settle things down, Art Bettge, Moscow’s mayor, pleads with the police to release more information. All they have said publicly is that there is no threat to the public, yet the place is swarming with cops. He wants a guy in uniform to say something into a microphone that’s at least slightly reassuring.

But Chief Fry won’t budge, so the mayor seizes the initiative. He gives an interview to the New York Times, a respectable outlet, but in this he is quoted as speculating that the murders were ‘a crime of passion’.

Far from soothing people, all this does is fan the rumour bonfire.

Social media is rife with gossip that Ethan, the one man in the murdered group, was part of a love triangle.

On TikTok, Reddit and the like, people are suggesting that drugs were involved and that the Idaho Four, as they have come to be known – Kaylee, Ethan, Xana and Maddie – deserved to be murdered. In the dark corners of the internet, conspiracy theories abound, including that the victims were gagged and bound. Murder-suicide is floated as a theory.

Accusations are hurled at the surviving housemates. Fingers point at the group of friends who sat weeping on the kerb outside 1122 King Road on the day the bodies were discovered, with commentators identifying which ones they think are the killers. Behind the chaos and confusion, the thought in every anxious head remains: what if this animal is still here?

Chief Fry finally decides to hold a press conference. He confirms that the four victims were stabbed and that the weapon hasn’t been found. There also appeared to be no forced entry into the home. He adds: ‘We believe this was an isolated targeted attack. We do not have a suspect at this time, and that individual is still out there.

‘We cannot say there’s no threat to the community, so please stay vigilant, report any suspicious activity, and be aware of your surroundings at all times.’

It’s too little, too late and far from reassuring. The gossip, the speculation, the fear continues. And spreads. Fascination with the Idaho Four case is now so extensive that a Facebook group page is launched and becomes the fastest-growing page about a true crime in the network’s history. Overnight, 3,000 people request to join. In a few weeks, it will have 200,000 members.

It is set up by friends Kristine Cameron and Alina Smith, who have founded true-crime Facebook pages before, ten in all, including one about the disappearance of Madeleine McCann. Idaho, with its four victims, all of them bright, smart, attractive young people who were popular and on social media, is an obvious winner. And yet the speed at which the page takes off shocks even its founders. It seems to be filling the void left by the Moscow police’s reticence.

Almost everyone has an opinion about ‘Hoodie Guy’, the mystery, masked character apparently spotted at the house at the time of the killings, and the roles of Bethany, Dylan, Jake, Jack, Emily and Hunter, the victims’ friends.

But one contributor stands out. He calls himself Pappa Rodger and he seems to have a remarkable inside knowledge of the case. He says, on the evidence so far released, the murder weapon was a large, fixed-blade knife and that it’s likely a sheath has been found. This is actually true, but there has been no public mention of a knife sheath.

When challenged on his theory, he is insistent to the point of aggression and rudeness, prompting a contributor he’s been debating with to tell him ‘you sound like a psycho’. Other members of the Facebook page message Kristine and Alina asking who the heck Pappa Rodger is. Why is he so arrogant? And why is he focusing on the knife sheath?

He is now posting fairly regularly, sometimes multiple times a day. And his questions and opinions contain increasingly dark thoughts as well as a certain macabre insight. ‘I believe the killer(s) came from the high side of the house. They were covered in blood after the attack… The kitchen was dripping blood but the police won’t admit it.’

Kristine googles Pappa Rodger but all that pops up is a reference to Elliot Rodger, the 22-year-old incel – an involuntary celibate, a reluctant virgin – in Santa Barbara who in 2014 murdered six people as revenge for all the women who wouldn’t sleep with him.

Kristine clocks this, but the connection seems too vague for her to do anything dramatic like report him to the police.

His posts get wilder and wilder, needling other members of the group. This Facebook page is meant to be a place to discuss the murders, not rant. He’s snide about other contributors. He taunts the police. He suggests the killer has a sexual dysfunction. He speculates that the killer was inside the house for just 15 minutes.

On December 22 he posts: ‘The killer is not in the victims’ immediate circle.’ And two days later that he thinks the assailant has probably left the area.

This catches the attention of police chief Fry, who has a team tracking all the social media discussions about the case, including the Facebook page. By now the police in Moscow, aided by the FBI, have a good idea of who their suspect is.

And Pappa Rodger is right. The suspect is not in the victims’ immediate circle. And, yes, he has left the area. The question for the investigator is: Why is Pappa Rodger right? Is it because he knows the suspect? Or because he is the suspect?

TEN MILES away from Moscow, at Washington State University in the town of Pullman, the behaviour of a certain PhD student is causing concern. When he was introduced to a class of freshers back in September as their new teaching assistant, Cassie Handziak, for one, found him off-putting.

A tall, thin guy with bulging eyes, he stared at her. Cassie’s neighbour whispered to her: ‘This guy is weird’. ‘Hi, I’m Bryan Kohberger,’ he told the class, informing them that he would be the person grading their papers. Cassie sees Kohberger, 27, twice a week, every time she has a class with Professor John Snyder. He doesn’t say anything, just stares.

He is super-communicative, though, in his grading, clearly putting lot of thought into marking her papers. He gives her As, which puzzles her because she doesn’t think she’s that good. She wonders if he has an ulterior motive.

She then discovers that, with other women on the course, he’s not so generous with their grades. He also writes pages and pages of comment, putting them in their place, putting them down.

They think he is tough on them simply because they’re women. And they are complaining to the professor about him.

In a revealing conversation with Ben Roberts, one of the men on the course, Kohberger makes no bones about his belief in traditional gender roles – men as bread-winners, women as home-makers. He maintains the women on the course are wasting everyone’s time pursuing master’s degrees.

Then he says something that Ben finds utterly creepy. ‘I can walk into any social gathering and

get any girl I want,’ Kohberger brags, which is an extraordinary thing to say, given his weird physical appearance.

What he doesn’t reveal is that he has seen a girl he wants and cannot get: a beautiful girl with long blonde hair and blue eyes named Maddie. He knows where she lives, at 1122 King Road in Moscow.

There is now a faculty meeting at which Professor Snyder confronts Kohberger with the complaints that he’s grading the female students unfairly and interrupting them in class with misogynistic comments. That he stares at them and positions himself by the door so they have to get uncomfortably close to him to exit the room. One claimed he followed her to her car.

Kohberger is having none of it. He’s angry and defiant, and goes bright red, clenching his fists so hard that his knuckles turn white.

‘They deserve what they get,’ he says, and suggests the women ought not to be in the classroom anyway because they’re just not clever enough and what they’re being taught is beyond them. Snyder acknowledges that Kohberger is smart, but he has a big ego and a high opinion of himself.

He is given a month to mend his ways but his behaviour is unchanged and he is confronted once again about it.

He is sacked as a teaching assistant, and his future as a PhD student is under review. He had come to Washington State from Pennsylvania, his home, hoping to reinvent himself. But his dream of a new life, a new persona, is imploding.

Back in Moscow, as the weeks go by since the slaughter at King Road, the police are making slow but solid progress in identifying the killer, though they won’t say it publicly.

That knife sheath found at the scene is at last yielding results.

The DNA on it was run through the FBI’s database of fingerprinted individuals but came up empty. It was then sent to a sequencing and genomics lab in Texas, using a new methodology to determine genetic genealogy and build a family tree around it.

Investigators have also sent off 103 pieces of evidence, including hair, fingernail clippings, and footprints, to local labs for testing.

Law enforcement teams have spoken to more than 100 people so far. A team monitoring CCTV cameras is homing in on a white car seen doing three passes around the King Road house between 3.29am and 4am on the day of the killings. At 4.04am, it made a three-point turn near the residence, went back and forth on King Road, then disappeared behind the house. It reappeared at 4.20am and left at high speed. FBI vehicle specialists identify it as a white Hyundai Elantra.

Local law enforcement agencies are alerted to be on the lookout for it. Over in Pullman, it is spotted in a student housing car park.

It is registered at the university as belonging to a student named Bryan Kohberger. And the same name surfaces when the results of the DNA check on the knife sheath finally come through, revealing a genetic connection to a Kohberger family from Pennsylania. It’s not conclusive. The procedure is a new one and untested. But it’s a giant leap forward in finding their suspect. The investigation is closing in.

Kohberger’s mobile phone records reveal that he was outside 1122 King Road at least 12 times between August 21 and November 13 – almost always late at night, cloaked in darkness. The theory emerging is that he was watching and waiting for Maddie after he saw her in the restaurant where she was waitressing and asked her out but she rejected him.

The investigators now do a video trawl of Pullman – where Kohberger lives – for the night of the killings and they see that at 2.44am his car is headed south on Route 270, the road that connects Pullman to Moscow. A few minutes later, his phone stops reporting to the network (or any network) and doesn’t come online again until 4:47am.

The police are coming to the conclusion that between those times, a masked intruder fitting Kohberger’s description entered 1122 King Road and stabbed Maddie Mogen, Kaylee Goncalves, Xana Kernodle, and Ethan Chapin to death.

By now Kohberger has left the North-West states. He’s driven across America back to his family home in Pennsylvania for Christmas, though there’s doubt about whether he’s going to return to Washington State where his career has hit the buffers.

Outside his parents’ home, an FBI surveillance team is hiding in the woods tracking his every move. To their astonishment, at 4am, he walks out carrying a garbage bag and wearing medical gloves. He dumps the bag in his neighbour’s dustbin, then scurries back home.

A few hours later he’s depositing more garbage in neighbours’ bins. Back and forth. He carries out bags several times in the hours to come. Always wearing gloves. What is he trying to hide?

Surreptitiously, the FBI agents raid the bins and fish out the rubbish. This is flown to the state laboratory in Idaho to be checked for DNA. What comes back is disappointing. Kohberger’s DNA is not in the trash. He has worked overtime to conceal it. But his dad’s DNA is.

And it’s a near match – 99.9998 per cent – with the DNA on the knife sheath found at the scene of the crime. This is more than enough for a judge back in Idaho to put his  signature to a probable-cause affidavit, which is then emailed to Pennsylvania where an arrest warrant is issued.

The Pennsylvania State Police SWAT team prepares for a night raid, readying the explosives, the flash-bangs, they’ll use for ‘dynamic entry’. They throw one through the front door and a diversionary device through the back window. The loud bang and the bright light stun the occupants and give the team time to get inside.

They find Bryan Kohberger awake, dressed in shorts and a shirt. He’s standing in the kitchen wearing medical-type gloves and putting trash in zip-lock bags. They surround him at gunpoint, zip-tie his hands, and stuff him in a police car. Then they ransack the house and his car for anything and everything.

They take away an assortment of clothing, including black face masks, hats, gloves, boots. They take his phone, laptops, hard drives, computer, as well as three knives – including a large, sheathed Taylor Cutlery knife – a gun (a Glock 22), and three magazines.

There’s also a poster of a man’s face in profile with a naked woman erotically arched backward, cleverly drawn into his frontal lobe. It points to the mind of a misogynistic incel who planned a murder as vengeance for all the women who would not sleep with him.

In custody at last, he is charged with four counts of first-degree murder. It is December 29 – 46 days since the killings – and the police have their man. For the next two and a half years he will maintain his innocence and defy the police to prove he killed the Idaho Four.

Until earlier this month when he pleaded guilty in a plea bargain to save him from the death penalty.

At his sentencing this week, it is expected he will be given four life terms in jail.

• l Adapted from The Idaho Murders by James Patterson and Vicky Ward to be published by Century on July 31, priced £20. To order a copy for £18 (offer valid to 02/08/25; UK p&p free on orders over £25) visit mailshop.co.uk/books or call 020 3176 2937.