Police have today widened their desperate search for the knife-fixated fan of X-Men character Wolverine suspected of stabbing three members of his family to death.

Bodybuilder Jed Allen, 21, is the prime suspect in the investigation into the killing of his half-sister Derin, six, his mother Janet Jordon, 48, and her boyfriend Philip Howard, 44.

The bodies of all three were found with knife wounds at the home the Wolverine fanatic, who appears to be fascinated with knives and axes, shared with them in Didcot, Oxfordshire.

Last night armed police and officers with sniffer dogs closed and began searching the Oxford University parkland where the stocky and tattooed bodybuilder once worked as a gardener.

But today the 70-acre area in the city, which was being guarded by Thames Valley officers, was open this morning, suggesting they do not believe he is hiding there.

Jed Allen's family last night pleaded with him to hand himself over to police, 36 hours after he disappeared.

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Manhunt: X-Men fanatic Jed Allen, pictured brandishing knives like Marvel comic hero Wolverine, is the prime suspect in the investigation into the killing of his half-sister Derin, six, his mother Janet Jordon, 48, and her boyfriend Philip Howard, 44.

Killed: Janet Jordon, 48, and her six-year-old daughter Derin, were found dead in their Oxfordshire home and are believed to have suffered stab wounds

Victims: Philip Howard, 44, right, Jan Jordon, left, and her six-year-old daughter, Derin, left, were stabbed to death in their Oxfordshire home. Police are hunting for 21-year-old Jed Allen in connection with their murders

Wanted: Police named Jed Allen, Miss Jordon’s 21-year-old son, as a suspect for the triple murder

Doting brother: Allen at 14 with his half-sister Derin. The little girl, right, now aged six, was found dea

Last night, a cousin of Jed Allen described his family’s profound shock at the murders.

Tyler Clarke begged the suspect to give himself up to police, adding: ‘No-one can believe what happened’.

He told The Sun: ‘The first thing I knew about it was when I saw it on the news. We just want to know why. But only Jed knows what’s happened.

‘If we could send a message to Jed it would be “give yourself up”.’

His plea came as tributes poured in for victims Philip Howard, 44, Janet Jordon, 48, and Derin Jordon. Friends and well-wishers visited the crime scene where they placed flowers and tributes.

One handwritten note read: 'You are my family and always will be.

'I will miss you all each day. You have all left a massive void in my heart which will never be filled. I love you all so much, Jan, Phil and my Dezzy Doo.'

Others left photos showing Janet and Phil playing with Derin.

Neighbours described Derin as a 'lovely little girl' and said they often saw her on her bicycle on her way to school with her mother by her side.

One, Sheila Welch, said: 'They are new neighbours and had only been here a couple of months. They were a lovely mother and a little girl. They always looked so happy.'

Sealed off: Police officers today still guard Vicarage Road in Didcot following the discovery of the three bodies on Saturday night

Crime scene: The bodies of all three were found with knife wounds at the home the Wolverine fanatic, who appears to be fascinated with knives and axes, shared with them

Tribute: Mourners have tied ribbons to a lamppost close to the house where they were found dead with stab wounds

Manhunt: Armed officers in riot gear and dog squads were seen entering the 70-acre park this afternoon

Crime scene: The family’s semi-detached council home in Didcot, where the bodies were found on Saturday

Tributes: Flowers and soft toys were left at the end of the road where the bodies were found in Didcot

Touching: A handwritten note left near the property where the bodies were discovered last night

Another former neighbour said Derin was often seen cycling with her mother.

The man, who did not want to be named, said: 'She was really nice, she used to smile and say 'hello' when she saw you in the street.'

As detectives warned the public not to approach the 21-year-old, pictures also emerged online of Allen clutching an axe and a 10-inch hunting knife.

In one photo, he is seen with blades between his clenched fingers like the Marvel comic superhero Wolverine in the X-Men films.

Neighbours suggested that Allen – who has a distinctive spider tattoo on his left hand - had been struggling to come to terms with the breakup of his biological parents' relationship and often appeared sullen and introverted.

And on his Facebook page he wrote recently about how his job had 'turned sour already' and that he was 'fed up of being treated like dirt'.

In another, he wrote: 'I've decided there is no time of day that I function well.'

Found dead: Jed Allen's mother Janet and his half-sister Derin. Police are continuing to hunt for Allen

A photo of a knife in what appears to be Jed Allen's hand that was posted on his Instagram account

Armed police erected a blue tent near the edge of park in Oxford as the search continued for Allen

Allen lived with his 48-year-old mother Janet Jordon, Philip Howard, 44, and their daughter Derin Jordon at a £300,000 council house in Didcot.

The bodies were discovered there on Saturday at 8.20pm after police were tipped off that something was wrong by a neighbour.

Forensic officers were combing the property yesterday. Although post-mortem examinations are yet to be carried out, police revealed the likely cause of death of the victims was stab wounds.

Allen's family had only moved to their semi-detached property two months ago from a smaller home a mile away.

Last night, Miss Jordon's former landlady spoke of the close bond between Jed Allen and his mother – but said his troubled upbringing was tarnished by her addiction to alcohol.

Jane Ilott, 68, said: 'I didn't know Jed as a 6ft man, I know him as a little fella who was really struggling. 'He absolutely loved his mum and she him, but she didn't know... drink was Jan's real love but she did love Jed.'

Detectives are looking for 6ft-tall Jed Allen (pictured), 21, following the murders in Oxfordshire

Suspect: Allen (pictured), has a distinctive spider tattoo on his left hand, police said

Police officers carrying riot shields were this evening seen searching parkland as they continue their hunt

Describing Miss Jordon as 'beautiful', Mrs Ilott added: 'She wasn't a bad woman, she was just an alcoholic.'

The pensioner explained that her former tenant moved into one of her houses in Bicester and Allen would visit.

She added: 'He was a typical teenager who did things in his own time – not necessarily when Jan wanted him to.

There's also the horror of it. If he did it, what caused him to snap?' Former neighbour Rizi Marina, 25, described Allen as a 'silent' type who often had a gym bag slung over his shoulder.

The IT consultant said: 'He was quite silent. He just said hi every time we saw him. Initially it was just the little girl living with the family, then the son came as well. We often saw him with a gym bag. He was a big guy.'

Police closed off Oxford University Parks as they narrowed down their hunt for former groundsman Allen

Thames Valley Police confirmed that the hunt had spread on to Oxford University (file picture) grounds

Police have shut down Oxford University Parks (shown above) in the hunt for the former groundsman

Police officers have cordoned off Vicarage Road in Didcot, where the three bodies were found yesterday

Forensics teams arrived as the search for Allen spread to university grounds. Above, police at the property

Allen's biological father Dave Allen lives half an hour away from the family home in Woodstock, near Blenheim Palace. His home has been put under police guard.

Thames Valley Police yesterday released a picture of Allen showing off the distinctive spider tattoo on his left hand in the hope it might aid the search for him.

Officers cordoned off Oxford University Parks as part of their search and were also seen to erect a forensics tent.

Detective Superintendent Chris Ward said the search for Allen had spread to the grounds of Oxford University.

He warned the public not to approach him, but stressed that police do not think he poses an imminent danger.

He said: 'In relation to the search for the suspect, we are still carrying out a number of searches. Some of those searches are with armed officers.

Three bodies were discovered at a house after officers were called by a member of the public on Saturday

Allen's family had only moved to their semi-detached property (road pictured above) two months ago

'There is a very small number of armed officers who are assisting with that search. That's purely for the safety of the searching officers.

'Allen was a groundskeeper at Oxford University. There are a large number of officers who have been deployed to find the suspect.

'We are searching the grounds of Oxford University. There are a number of addresses we have already visited in Didcot, as well as an open search in Oxford.

'It is very important that we locate him as quickly as we can.'

He described the incident as a 'tragic and sad event' and offered his condolences to the family.

'The families of the victims have been informed and they are being looked after by specially trained officers,' he added.

Gardner who idolises film hero Wolverine

This is Jed Allen posing as his movie hero Wolverine.

The triple murder suspect wears a black hoodie and a cap as he poses in one of several images on his Facebook page.

He stares at the camera as he holds three blades between his fingers to mimic the superhero from the Marvel comic books and X-Men films.

Posing for the camera: Jed Allen brandishes knives like Marvel comic hero Wolverine

Elsewhere online, Allen has posted numerous pictures of the character and was even given a Wolverine inspired 21st birthday cake.

Another picture shows his right hand, emblazoned with a scorpion tattoo, clutching a ten-inch hunting knife. He also has a large spider tattoo on his left hand and a tattoo of a growling bear on his chest.

Last year he posted a series of messages of frustration and anger about his life.

In one he wrote: ‘Whoever doesn’t like me just remove me from your lives so I can put you out of my misery. You know who you are.’ And two weeks earlier the former Oxford University groundsman wrote: ‘Works (sic) turned sour already. Fed up of being treated like dirt.’

Whoever doesn’t like me just remove me from your lives so I can put you out of my misery. You know who you are Message posted by Jed Allen

Days earlier he added: ‘Was just about to say I’m not a morning person. I’ve decided there is no time of day that I function well.’

Allen, a keen bodybuilder, was born in Oxford to Janet Jordon, 48, and David Allen, 47, and was brought up in the town of Woodstock, near Blenheim Palace.

He enjoyed a modest blue-collar upbringing and attended Marlborough School – a Church of England state school in Woodstock, Oxfordshire, which has since been granted academy status.

At some point the couple split up and his father is understood to have had another son and a daughter with a new partner. That couple have also since split up.

Meanwhile his mother moved with her son to Didcot to make a fresh start. Six years ago she gave birth to a daughter called Derin.

Miss Jordon posted numerous touching pictures of Derin on her Facebook page in her daughter’s early years, including one of Allen at the age of 14 smiling as he holds his half-sister as a baby.

But life in the fragment family home was not always straightforward. Miss Jordon’s relationship with Philip Howard, 44, was said to be ‘on-and-off’.

In December 2012, Miss Jordon appeared before magistrates on several charges of shoplifting to which she pleaded guilty.

The mother of two admitted stealing two packets of nose studs worth £14 from Claire’s Accessories in Didcot in October 2012.

She also stole towels, decorations, candles and charity cards worth £32 from Cargo Home Store and gift cards worth £20.25 from another store the same day.