I brought down the Scalp Hunter serial killer... he despised me and kept a sick secret to his grave

Serial killer John Sweeney disgusted seasoned detectives with the gruesome details of his horrific crimes, but even they were shocked at the arrogance of his behaviour in court as he stood accused of murdering two former girlfriends.Sweeney, who called himself the Scalp Hunter, butchered Melissa Halstead and Paula Fields before dumping them into canals in London and the Netherlands.But in the dock at the Old Bailey in 2011, the killer, believed to have slaughtered even more women during a 'demonic' orgy of violence spanning decades, refused to listen to the damning evidence against him.In an act of staggering arrogance, he stuck earplugs in to block out any references to his crimes and then refused to leave his cell for sentencing after being found guilty.He was given a whole life tariff for his evil and died behind bars from cancer aged 69 at HMP Whitemoor, Cambridgeshire, last week.But Sweeney saved a final act of wickedness for his dying breath, taking the secrets of where he buried the remains of victims to the grave.The monster's cowardice and arrogance was of little surprise to retired Detective Chief Inspector Howard Groves, who helped catch the killer and bring him to justice.He told The Crime Desk: 'I always wondered and hoped whether he would have it within him to say, "This is what happened, this is where their remains are, or what I did with them".'I feel for the families who will never have closure – that would always be something that they can't change. John Sweeney was jailed for life in 2011 after murdering former girlfriends Melissa Halstead and Paula Fields and throwing their mutilated bodies into canals in England and Holland Halstead was an American-born model, originally from Ohio, whose torso was discovered in a Rotterdam canal on May 3, 1990 Sweeney went on to kill 31-year-old mother Fields, whose body was found inside six holdalls floating in the Regent's Canal, London, in 2001'I suppose he's somebody who feels that they have the upper hand, "I will always take this secret with me to my grave". There are people who are like that. There's no humanity in them, even at a certain point in life where they may reflect on what they did and do the right thing. 'I hoped - although I always kind of felt this would be the final outcome - that he would never divulge.'And it's because he now knows that everybody wanted him to say what happened and where the remains are, but he has to have the final say. He has to have that power, because it is a power trip by not disclosing to us.' I know why Jack the Ripper was protected for so longHi, I'm Alex Matthews, Editor of The Crime Desk.In 2014, we revealed the bombshell evidence identifying Aaron Kosminski as the fabled Jack the Ripper. Now, we can reveal his astonishing connection to the Freemasons and claims this motivated his killings and protected him from life in prison. Sign up here to get our exclusive piece for free. Sweeney dismembered Ms Halstead, 33, an American photographer and former model.She was found in a bag in a canal in Rotterdam in May 1990. Her remains were not identified for 18 years.And schoolboy anglers discovered Ms Fields, 31, in ten pieces and floating inside six holdalls in Regent's Canal, Camden, north London, nearly 11 years later in February 2001.Officers using advances in DNA linked Sweeney to the crimes when convicting him of an axe attack on ex-girlfriend Delia Balmer, a nurse, who was saved by a neighbour who chased him off with a baseball bat in Kentish Town.The carpenter - born in Kirkdale, Liverpool - boasted of his violence in hundreds of blood-curdling paintings and poems found at his bedsit, alongside an arsenal of weapons including two sawn-off shotguns and a pistol.Pictures depicted women with hands and feet chopped off, references to '666' and Sweeney as Satan.A twisted poem he penned read: 'Poor old Melissa. Chopped her up in bits. Food to feed the fish. Am*dam was the pits.'Detectives questioned Sweeney over the disappearance of three other former girlfriends but he was never charged with any further killings. Dutch police also investigated claims that Sweeney killed two German men.Police suspect he may have slaughtered others in the UK, the Netherlands and elsewhere in Europe where he told them he had '30 to 40' relationships.Mr Groves, who retired in 2014 having served 30 years in the Met, recalls the intense hatred Sweeney had towards him in court.'I know that he despised me because of the investigation,' he said. Halstead's body was thrown into the Westersingel canal in Rotterdam in the Netherlands A drawing by Sweeney which the prosecution said is a portrait of him and Melissa Halstead'He didn't like me because my name was mentioned to him at some point and he made a flippant remark. But that didn't surprise me and I didn't expect anything else. So, I wasn't going to lose any sleep over that.'He sat there with earplugs in his ears for the majority of the trial. I think that was just the contempt that he had for the officers, family members and jury. He was not really taking much stock of what was being said.'My view is, if you're not guilty, because that's the reason why you go to court and through the whole thing of the defence and prosecution, and you stick plugs in your ears, you're basically saying, I don't want to hear any of this.'Maybe he knew what the outcome was, so that's just his way of distancing himself from everything that was happening around him.'Sweeney's conviction was the first time British police had teamed up with detectives from another country to investigate a series of murders, although they previously cooperated on organised crime.'There wasn't that much forensic evidence for us to go on,' remembers Mr Groves, who turns 70 next month.'A lot of [the case] relied on the artwork that he'd done and the testimony of other people who had some association with him over a period of time.'The investigation was meticulous, painstaking, and yes, it was a challenge for the team.'Asked if Sweeney is the most evil perpetrator he'd faced, Mr Groves said: 'Anybody who takes another person's life, under the circumstances where you define it as murder, I have contempt for whoever they may be.'I haven't singled him out in a separate box from the other people that I have dealt with because it is heinous, irrespective of whether it be John Sweeney or another person.'His case was much more in the public domain. I couldn't have solved that murder without the team that I had behind me.'But his sadness remains with the victims' families, he adds. In 1994, Delia Balmer was attacked by Sweeney, pictured together above, with a hammer and an axe. She was saved by a neighbour who chased Sweeney off with a baseball bat Another drawing by Sweeney showed Halstead in the middle of the collage, then again in close-up with the words 'RIP''They have not had closure in a way that they would like it,' Mr Groves concludes.'I was always fearful that we would get this information that he's passed away, and suddenly for the families it will not necessarily be a happy day.'Even if he were to leave a letter for somebody to open and read with his secrets, he's no longer there to make their feelings known to him directly or indirectly.'Jailing Sweeney, judge Mr Justice Saunders said: 'These were terrible, wicked crimes.'The heads of the victims having been removed, it is impossible to be certain how they were killed.'The mutilation of the bodies is a serious aggravating feature of the murders.'Not only does it reveal the cold-blooded nature of the killer, but it has added greatly to the distress of the families to know that parts of the bodies of their loved ones have never been recovered.'A book by survivor Ms Balmer was turned into a 2024 four-part ITV drama Until I Kill You in which she is played by Anna Maxwell Martin. Shaun Evans is cast as Sweeney, the LSD addict who would terrorise her by holding a gun to her head to play Russian roulette.Sweeney lived most of his early life in Skelmersdale, Lancashire.In 1982, he was bound over to keep the peace after threatening Anne Bramley, his then wife with whom he had two children. Officers found him hiding in a wardrobe at the couple's home armed with a hammer and an axe.A prison service spokesman said: 'These were horrific crimes and our thoughts remain with the victims and their loved ones.'As with all deaths in custody, the Prisons and Probation Ombudsman is investigating and it would be inappropriate to comment further before the conclusion of its findings.'