Sky News can reveal the "disgusting" police WhatsApp message sent in the aftermath of the killings of Barnaby Webber and Grace O'Malley-Kumar on 13 June 2023.
Their families are horrified by the language used by an officer when discussing the stabbings with colleagues.
Valdo Calocane, 32, a paranoid schizophrenic, stabbed the two 19-year-olds to death as they walked home from a night out before flagging down and killing 65-year-old school caretaker Ian Coates.
At the time, one officer messaged colleagues on a WhatsApp group.
The message said: "So 2 students on Ilkeston road have been proper butchered, 4 section [officers] turned up and tried to hold their inners in. Suspects then made off and attacked a man in a car on magdala [road] and stabbed him to death."
Another officer, PC Matt Gell, then shared the message outside of the police WhatsApp group with his wife and two friends.
The families of Barnaby and Grace learned of the contents of the message in February but were so disturbed by its contents that they have only felt comfortable publicising it now, despite the pain it causes them.
Grace's father, Dr Sanjoy Kumar, said the message is "so disgusting".
"Would anyone with a child, a mother, a relative use words like that?" he asked.
"Why have police in Nottinghamshire forgotten that these are our dear and beloved children they are referring to? I have tears in my eyes every time the message echoes in my head," said Dr Kumar.
"The message is as barbaric as the crime for me."
Nottinghamshire's chief constable Kate Meynell acknowledged to Dr Kumar that some of the WhatsApp message was "crude and distasteful".
'Callous and degrading'
Emma Webber, Barnaby's mother, has now written an open letter to the members of the WhatsApp group after requests to meet the officers involved were rejected by the force.
"The callous, degrading and desensitised manner of your comments have caused more trauma than you can imagine," she wrote.
"When you say 'a couple of students have been properly butchered' did you stop to think about the absolute terror that they felt in the moment when they were ambushed and repeatedly stabbed by a man who had planned his attack and lay waiting in the shadows for them?
"When you say 'innards out and everything' did you think about the agony they felt and the final thoughts that went through their minds as this vicious individual inflicted wounds so serious that they had no chance of surviving?"
Mrs Webber's letter also calls for tougher action for the officer involved.
"Anyone who can witness the details of such a horror as happened... and refer to lost children as butchered animals; should seriously consider their position," she says.
"So, to the author of that message, who we understand has received a management warning. I pray you will read this and pause for a while.
"Dig a little deeper for compassion and care. Show the respect in the future that you did not afford Barney."
PC admits 'lapse of judgement'
The officer who wrote the message did not face a misconduct hearing but received 'management intervention'.
In January, PC Gell, who forwarded the message to people outside the force, was found guilty of gross misconduct and given a final written warning after he looked up records relating to Calocane when he had no part in the investigation.
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The panel at the hearing agreed with his acknowledgement that he had "a lapse of judgement".
A special constable was also sacked for viewing body-worn footage of the two students in their final moments.
Almost 180 police staff were found to have viewed material relating to the case, with 11 of them having no "legitimate reason" to do so.
Nottinghamshire Police referred itself to the Independent Office for Police Conduct after the families raised a number of concerns over the investigation and police conduct, including the force's failure to inform relatives their Professional Standards Directorate was investigating officers.
The College of Policing is also conducting a review of how the force handled the case.
Deputy Chief Constable Steve Cooper previously told Sky News that action over the WhatsApp message was taken "immediately".
"Some of the words were crude and distasteful. It was a single message and no images were taken or shared," he said.

The animals, with saddles and bridles, were seen running on the road near Aldwych on Wednesday morning.
Pictures and videos of the horses were shared on social media, one of which showed a black 4x4 with blue lights following the animals.
Sky News understands they were Household Cavalry horses.
An army spokesperson said: "A number of military working horses became loose during routine exercise this morning.
"All of the horses have now been recovered and returned to camp. A number of personnel and horses have been injured and are receiving the appropriate medical attention."
City of London police said two loose horses had been caught on the Highway near Limehouse.
"At around 8.40am, we were called about horses that had become loose and were travelling through the City," the force said in a statement.
"Our officers have contained two horses on the Highway near Limehouse. We're waiting for an army horse box to collect the horses and transport them to veterinary care."
The Metropolitan Police said in a statement: "We're pleased to confirm that all of the horses have been accounted for. We are continuing to liaise with the army."
In an earlier statement, a spokesman for the force said: "We are aware of a number of horses on the loose in central London."
Ambulance sent to scene
A London ambulance service spokesperson said: "We were called at 8.35am today to reports of an incident with a horse at the junction of Chancery Lane and Fleet Street.
"We sent resources to the scene including an ambulance crew and members of our tactical response unit.
"The incident is still ongoing and we are working with our emergency services partners."

A state of emergency in Ecuador was declared after his escape from prison, and the government battled to regain control of the country's jails from gangs.
President Daniel Noboa has vowed to eradicate violence and restore order, but three months on his forces have yet to recapture Macias, 44, the leader of the notorious Los Choneros gang.
Fito was serving a 34-year sentence for drug trafficking and murder. His escape in January occurred on the day he was scheduled to be moved from La Regional prison to a maximum security facility.
Despite being behind bars, he was able to continue to direct the activities of Los Choneros. He also enjoyed access to mobile phones and the internet, watched TV and kept pets.
"His prison cell basically resembled a hotel room," says Annette Idler, a professor of global security at the University of Oxford. "He had access to women who were brought to him," she adds. "It was a luxury room for him."
Colourful murals of the gang leader were even daubed across the walls, including one of him flanked by two assault rifles.
Music video glorification
Fito also managed to star in a professionally produced music video, parts of which were filmed inside his prison, exalting the drugs kingpin as "el jefe y patron" - the boss.
There has been no explanation from authorities about how a film crew was able to gain access to one of Ecuador's most notorious criminals. Meanwhile, El Corrido del Leon - the Lion's Ballad - has racked up nearly 900,000 views on YouTube.
"It was glorifying him as this good and honest guy - how does that happen?", says John Murdy, a University of Chicago PhD student who has spent years researching Ecuador's prisons. "Fito is unique."
This was only possible, Prof Idler says, because of corruption in the Ecuadorian prison system, with prison guards severely outnumbered and under pressure.
The choice between silver and lead
"It's something that resembles Pablo Escobar - the choice between silver and lead. Either they receive a bribe or they're just shot."
Those same words are emblazoned on the prison wall mural of Fito - 'plata' (silver) and 'plomo' (lead).
Prison guards faced with overcrowded jails and not enough support are vulnerable to this kind of pressure from the gangs, who can find out where their families live, and often end up on their payroll.
Unable to fully control their prisons, authorities resorted to sorting new inmates by their gang affiliation.
"In effect the Ecuadorian state is giving prison wings over to gangs, which means they are able to consolidate their power and have a base of operations," Murdy says. They can then collect weapons like machine guns, machetes and bombs, he adds.
Los Choneros, led by Fito, is one of the gangs authorities hold responsible for a spike in violence that reached new highs last year with the assassination of the presidential candidate, Fernando Villavicencio.
When Fito escaped La Regional prison on 7 January - his second jailbreak - the news spread around the world.
Roberto Izurieta, press secretary for the president, said "most likely" there was a leak of information that led to Fito's escape. He said the gang chief was tipped off "a matter of hours" before he disappeared.
Embarrassment for president
"It was a real egg-on-the-face moment for the new president," says Murdy. "Somehow Fito learned about this very high level security intervention and was able to escape without a gunshot fired."
But should it have come as such a shock? After all, he was not being held in a high security prison.
Prof Idler adds: "In a way it was not much of a surprise... because we know Fito had lots of control."
Three months later, Fito is still at large.
"On the one hand, it's surprising because Ecuador is working with the US and Colombia, who have good intelligence services - this should help in finding him."
'Endemic corruption'
But Prof Idler added that the "endemic corruption" in Ecuador means that it may be difficult to track him down.
"It's not clear where he actually went," she says. "Given that these criminal organisations operate across borders it's also quite likely that he is very well protected through his network, not just inside Ecuador but also in the wider region."
There was speculation that he might head to Argentina, where he had moved his wife and children. But they were deported back to Ecuador a couple of weeks after Fito's escape.
Amid suspicion that he might instead seek to pass through Peru to reach Bolivia, the Peruvian government strengthened security along its border.
Prof Idler adds: "The authorities' eyes are on him, but it's definitely plausible that he's still somewhere in the region hiding."
It remains to be seen when, or if, Fito will be hunted down. And even if he's recaptured and put back in prison, what then? Fito has already escaped prison twice, could he do it again?

The 61-year-old, who is Northern Ireland's longest-serving MP, was suspended by the party following his arrest last month.
In a statement at the time, the DUP said: "The Party Chairman has received a letter from Sir Jeffrey Donaldson MP confirming that he has been charged with allegations of an historical nature and indicating that he is stepping down as Leader of the Democratic Unionist Party with immediate effect.
"In accordance with the Party Rules, the Party Officers have suspended Mr Donaldson from membership, pending the outcome of a judicial process."
In his resignation letter, he said he would be strenuously contesting the charges.
Sir Jeffrey Donaldson had been arrested at his home in County Down the previous morning and taken to Antrim Police Station for questioning.
In a short statement, the Police Service of Northern Ireland confirmed that a 61-year-old man had been charged with "non-recent sexual offences" and that a 58-year-old woman, arrested at the same time, had been charged with "aiding and abetting" in connection with the offences.
Both will appear before Newry Magistrates Court in Co Down on Wednesday.
Sir Jeffrey, who has been MP for Lagan Valley for 27 years, was knighted for his services to politics in 2016.
He helped broker the DUP's £1bn confidence and supply deal with Theresa May's minority Tory government, when the party held the balance of power at Westminster between 2017 and 2019.
More recently, he had compromised and led his party back into the power-sharing government at Stormont, which it had boycotted for two years over post-Brexit trading arrangements.

The BBC Radio 2 presenter paid tribute to her mother for "teaching us how to love unconditionally" and said: "Your grace & your smile that lit up every room you were in, will light the stars to guide us."
Ball, 53, shared news of her mother's death on social media with a younger picture of her and the caption: "Sleep tight dear Mama."
Ball had announced her mother's "heartbreaking" diagnosis in early March, saying it had been an "extremely tough" time but "mum is being incredibly brave".
The presenter confirmed Gaby Roslin would "occasionally" replace her on The Zoe Ball Breakfast Show so she could spend time with her mother, who was later taken to a hospice.
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Ball announced her mother's death in an Instagram post on Wednesday saying: "Thank you for teaching us how to love unconditionally, to always show courage and empathy, and how, even in the darkest of days, laughter is the greatest of gifts.
"We are bereft without you but will hold so tight to each other."
Woody Cook, the son of Ball and her ex-husband Norman Cook better known as British DJ Fatboy Slim, also shared a tribute on Instagram.
"Today I say goodbye to Granny J, thank you for being a wonderful woman," the 23-year-old said, sharing a picture of his younger self with his grandmother.
Cook, who appeared on the reality series The Circle in 2019, also referenced his grandmother's late husband Rick Peckham.
He said: "The only person who always sent me a valentines card. I know you're with Rick now, give him a hug from me.
"I know he said once when you were panicking in a helicopter over the Jungle 'If you get lost, follow the river!' You'll find him at the end."