EXCLUSIVE: Margaret Parkes today issued a direct plea to 'Frankenstein' killer Allan Grimson in a desperate bid to find out what happened to her son, Simon Parkes16:14, 28 Jul 2026The mother of a sailor missing for almost 40 years today issued a direct plea to the "Frankenstein" killer feared to have murdered him, begging: "Tell me what you did to my son."‌Margaret Parkes, 80, is adamant radio operator Simon fell victim to evil Allan Grimson, 66, when HMS Illustrious docked in Gibraltar in December 1986. Detectives investigating Simon's disappearance closed the probe into Grimson last December after drawing a blank.‌But Margaret says she is convinced the double killer - who was found guilty on Monday of sexually assaulting four men and boys - was behind her son's disappearance. And she says she still hopes for justice after nearly 40 years despite Grimson denying involvement in Simon's disappearance.‌In a direct message to Grimson, Margaret said: "Please tell us what happened to Simon." Calling for police to reopen the investigation, she added: "How do you get in to the head of a man like that? We want him to tell us what he knows, where Simon's body is, we would want that, but he's in denial now. All these years we've done all we can to find out information and keep the investigation open."Grimson - nicknamed the Frankenstein Killer, due to his 6ft 2in frame and large forehead - was jailed for life in 2001 for murdering two young men who served with Simon on aircraft carrier Illustrious. He was convicted of battering to death Nicholas Wright, 18, of Leicestershire, and barman Sion Jenkins, 20, of Newbury, Berkshire.‌Grimson - who once claimed murder was "better than sex" - had invited the two Navy seamen to his flat and killed both with a baseball bat before dumping their bodies on two dates exactly a year apart in the 1990s. That date was December 12th - the same date that Simon vanished.As he was sentenced in 2001, the judge branded Grimson a “serial killer in nature if not by number”. Yesterday he was found guilty of 13 offences against four other men and boys, including a 14-year-old, in the 1990s. Winchester Crown Court heard he told police one of his sex attack victims was "lucky" to be alive because he would have killed him if his friend was not sleeping on the sofa.‌He brought the teenager to his flat in Portsmouth, Hampshire, and sexually assaulted him - weeks before his killing spree. Grimson is said to have told police in 1999: "If you're going to rape somebody, to get away with it, kill it. And that's the only way you can do that."For more than four decades Grimson has been linked to Simon's disappearance but has never been prosecuted. Grimson was serving on board the HMS Illustrious aircraft carrier at the same time as Simon.‌Now Margaret says she prays for a resolution so an inquest can be held and she can get answers about her son's disappearance. She says she has spent more than half her life in limbo and now hopes she can be issued with a death certificate if a coroner in Gibraltar is able to proceed.She said: "I was very disappointed that the investigation was dropped. Now we want to have an inquest so we can also be given a death certificate after nearly 40 years. We want someone to say that Simon is dead."I'm 80 now so we probably don't have much longer if you think of it that way. And I want the investigation to be reopened so Grimson can be prosecuted and we can get justice. We want answers. We've been submerged in this for 40 years, it's always there and it's always been a feeling of helplessness. It's so painful."‌Police have carried out a string of searches in Gibraltar including at a cemetery and in a car park. Grimson has always denied being involved in Simon's disappearance.Six years ago, the Parole Board recommended Grimson be moved to an open prison as a first step towards being freed on licence. But his barrister, John Femi-Ola KC, said during his trial that Grimson’s chance of parole had been deliberately “stymied” when police began reinvestigating his contacts with four men and the Crown Prosecution Service gave the go-ahead for him to be charged.‌Mr Mr Femi-Ola told a jury at Winchester crown court that in 2020 the Parole Board recommended transferring Grimson to an open prison. The barrister described this as a “huge step” for Grimson, but said the authorities stepped in, approaching the four young males.Mr Femi-Ola said that when police contacted one of the alleged victims, he was hesitant about making a fresh complaint and asked what it would achieve. The officer replied: “If successful it would mean his parole is denied.”‌During Grimson’s trial in 2001, one psychiatrist called him a psychopath and the most complex of over 250 murderers they’d met. Grimson - who once claimed murder was "better than sex" - has since been diagnosed as suffering from a severe personality disorder - The same as serial killer Dennis Nilsen.As it cannot be treated, Grimson has served his sentence in prison, rather than being admitted to a hospital such as Broadmoor.TIMELINEDecember 12, 1986: Simon Parkes, from Bristol, vanishes after the the ship he was serving on, HMS Illustrious, docks in Gibraltar. The 18-year-old radio operator failed to return after a night out with crewmates, leaving his passport, belongings and Christmas presents on board the ship. He never returned and the ship returned to Portsmouth without him. Allan Grimson is serving aboard the aircraft carrier at the same time.‌December 12, 1997: Grimson bludgeons Nicholas Wright, 18, to death with a baseball bat after Wright rejected his sexual advances. The monster slices Nicholas' ear off with a diving knife, before slitting his throat. The next day, Grimson wraps Nicholas' naked body up – later telling police he felt a “tingling” sensation while doing so. He then dumps the naval rating’s mutilated body in a ditch.December 12, 1988: Grimson attacks and rapes Sion Jenkins, 20, in the same Portsmouth flat where he killed Nicholas before tying him up and putting him in a bathtub. As Sion begs to go home, Grimson beats him to death with a bat before dumping his body by the side of the A32. Sion's body is discovered four miles (6.44km) from Nicholas' at the side of country lanes north of Winchester in December 1999. Grimson confesses to his crimes in excruciating detail, telling police in a 1999 interview: "If you’re going to rape somebody, to get away with it, kill it.”April 5, 2001: Grimson is jailed for life for Sion's and Nicholas' murders. The judge recommends that he serve a minimum of 22 years, telling him he was a "serial killer in all but numbers". This sentence was increased to 25 years by the then Home Secretary. In 2008, Grimson won a reduction in his life sentence by three years. Following Grimson's conviction, Hampshire Police re-open the investigation into Simon's disappearance.‌June 8, 2003: Three detectives and a naval police officer return to Gibraltar to search for clues and spend a week investigating Simon's disappearance.December 2, 2019 - A week-long search is launched by detectives who carry out a dig at Gibraltar's Trafalgar Cemetery.August 7, 2023 - Nine officers travel to Gibraltar and carry out a small amount of excavation work at the Town Range car park as they "followed a potential further line of enquiry".‌January 19, 2024 - Police carry out further digs at the Town Range car park but fail to find any new information.July 4, 2025: Grimson - whose sentence expired on December 20 2021 - is denied his freedom. The Parole Board rejects his application on public safety grounds, with Simon's mother saying: "As a family, we are going through a life sentence not knowing what happened to Simon or where he is buried. It is only right, at least until he gives up that information, that he suffers the same."December 30, 2025: Police announce they are ending their investigation into Simon's disappearance. Hampshire and Isle of Wight Constabulary reveal, following the advice of the Crown Prosecution Service, that the investigation would be filed unless further information came to light.Article continues belowJuly 17, 2026: Grimson is found guilty of 13 offences against four men and boys, including a 14-year-old, in the 1990s. His trial is told that he told police in 1999: "If you're going to rape somebody, to get away with it, kill it. And that's the only way you can do that." He will be sentenced in November.