The 55-year-old victim was taken to hospital in a critical condition following the incident in Wakefield, West Yorkshire, on Saturday afternoon and died later that evening.
Another 55-year-old man has been arrested on suspicion of murder, and being the owner of a dog dangerously out of control in a public place causing injury.
The dog, a German Shepherd, that is thought to have been involved has been seized by police.
West Yorkshire Police initially received reports just after 1.30pm that an altercation had taken place on a footpath off Blacker Lane, during which the man was bitten by the canine.
The area is often used by walkers, according to officers.
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Detective Chief Inspector Michael Cox said: "Sadly, a man has died and it is really important that we understand the circumstances of what has taken place.
"We know that two people, one named Sophie, stopped to assist the injured man and direct officers."
Mr Cox added: "We would urge these two women to come forward to help us with our ongoing enquiries into this tragic incident.
"The initial altercation has happened in an area used by walkers and we are urging anyone who has potentially seen or heard any part of the exchange between these two men to please make contact."
Anyone with information should contact West Yorkshire Police.
Two cars were in a head-on collision on the M9 between junctions 3 and 4 near Athy at roughly 3am on Sunday.
One of the vehicles was travelling in the wrong direction - southbound on the northbound carriageway of the motorway, according to police, who have not confirmed how many people have died.
Garda Commissioner Justin Kelly said: "My thoughts are with those injured in this morning's collision on the M9. These family members were travelling innocently when they were struck by a vehicle being driven the wrong way down the motorway.
"This horrific incident, following the recent collision on the M50, shows how irresponsible and dangerous driving on the wrong-side of the motorway is.
"That, of course, should be self-evident, but what makes this reckless behaviour even more appalling is that, in some cases, it is being done for social media likes regardless of the potentially devastating impact it might have on innocent people and themselves."
He added: "As this particular incident has been referred to Fiosrú, the Police Ombudsman, I am constrained in what I can say, but I know that Gardaí do what they can to stop such vehicles while also taking into consideration all other road users."
Four people, who were badly injured, have been taken to hospital.
They include the female driver and front passenger of the second car. They are both aged in their 30s and remain in a critical condition.
A female rear seat passenger, aged in her 20s, is in a serious condition.
The third passenger, a child, is also in a serious condition.
The M9 from junction 3 to junction 4 northbound and southbound remains closed, and a forensic investigation is set to take place.
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A referral has since been made to Fiosru, the Office of the Police Ombudsman.
It said in a statement: "The referral was made following a fatal road traffic incident on the M9.
"One of Fiosru's on call team of investigators attended the scene and its independent investigation is ongoing.
"In line with its statutory remit, Fiosru's investigation relates to incidents involving contact with gardai (Irish police) where a member of the public has died or been seriously injured. A referral does not necessarily mean a garda or gardai have been accused of wrongdoing."
Officers have asked for any witnesses to come forward.
They are also appealing to those who were travelling on the M9 northbound or southbound between 2am and 3am on Sunday morning and who may have dashcam footage of the incident.
It happened late on Saturday in the village of Manzanedo de Valdueza, near Pontevedra, with pictures showing streets and cars deluged by mud.
Seven regions in the north and central region are under a yellow alert for storms and heavy rain on Sunday.
It comes about seven weeks after a huge wildfire in the Avila region west of Madrid was declared a national emergency and forced tens of thousands to evacuate.
Other wildfires in Spain, France, Greece, the UK and elsewhere continue to burn, with Belgium dealing with its largest on record.
Authorities said the fire had destroyed 3,000 hectares of land by Sunday morning and was very close to the German border.
The blaze is in the High Fens nature reserve, in the country's east, and has been burning since Friday when the temperature hit 37C.
It has surpassed a 2011 fire in the same area that was previously the country's biggest.
Firefighters from Germany and Luxembourg have joined the response, alongside the army and local farmers.
Tourists have been told to leave the area but so far no properties have been destroyed.
The fire was still spreading towards a municipal forest on Sunday, said Rene Dahmen, chief engineer at the Department of Nature and Forest.
"The situation is extremely difficult," Mr Dahmen said. "We need helicopter support."
The call for help has been answered - with three helicopters and two water-bombing planes being sent from Sweden, the Netherlands and the Czech Republic.
EU commissioner Hadja Lahbib said Belgium had activated the union's civil protection mechanism for outside support.
"The High Fens are burning. Belgium is not facing it alone," Ms Lahbib posted on X.
The fire is just under a mile from Germany, according to authorities in the town of Monschau.
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It's not currently expected to breach the border, but a little further inside Germany a separate fire has been burning in the Hurtgen forest.
The worst appears to be over and about 2,000 people in the village of Gey have been allowed home. The local government said there were no longer any open flames.
In Greece, two people died and others were injured on Sunday in fast-moving wildfires on the island of Salamina, a popular getaway for people from Athens.
Nearly 200 firefighters, 14 aircraft and helicopters have been deployed but authorities said strong winds were making the flames spread rapidly.
The fire department said the two who died are believed to have been a couple.
France is also dealing with a wildfire that began on Thursday and has burned 1,700 hectares in a pine forest in the southwest Landes region.
About 650 people have been forced to evacuate and around 500 firefighters are on the scene.
It's not far from the site of France's biggest fire for more than 70 years, which last month ravaged the Gironde region around Bordeaux and forced more then 220,000 to evacuate.
The blaze has now dissipated and tourists are being encouraged to return.
In the UK meawhile, soldiers from the Gurkha regiment have been sent to help in South Wales, where 14 wildfires are burning.
The 41-year-old, who resigned from his position as professor of sociology of education last week, was found dead at an address in Battersea, London on Friday.
On Saturday afternoon Windrush campaigner Sir Patrick Vernon launched a GoFundMe page in Dr Arday's memory, which has since received more than 2,000 donations.
Dr Arday's family said in a statement: "We would like to express our heartfelt thanks to those who have reached out following the tragic loss of our beloved Jason. We have been touched by the messages of love, condolences and acts of kindness during what is a deeply painful time for our family.
"We are incredibly moved by the generosity of those who have contributed in any way to Jason's funeral, memorial and associated costs. Whilst no sum of money will ever bring him back to us, the generosity you have shown is helping to ease some of the practical pressures we face while we try to come to terms with our loss.
"It has brought us some comfort to hear from the many people whose lives Jason touched as a family member, friend, colleague, teacher, academic, author or advocate."
Writing on the GoFundMe website, Sir Patrick paid tribute to the "pioneering" academic - and said he was "deeply concerned" about the nature and intensity of attacks directed at him after allegations of plagiarising his PhD thesis while at Liverpool John Moores University. Questions were also raised about Dr Arday's life history and claims in his forthcoming memoir Great and Unfortunate Things.
"I was also subject to media scrutiny for signing the letter of support and challenged in supporting Jason," he said.
Sir Patrick said the funds will help cover Dr Arday's funeral, memorial and associated family costs, as well as practical support for his family.
Stand Up to Racism co-convenor Weyman Bennett said in a statement that his death was a tragedy, and the "result of a racist witch hunt."
"For more than a week, the right-wing press, politicians and the far right have hounded Jason with the most vicious racism," Mr Bennett said.
"They are spreading the far-right lie that black people are only appointed because of the colour of our skin, rather than our ability.
"They have blood on their hands. Our thoughts are with Jason's family, but we are furious with those who are to blame. Enough is enough."
The anti-racism organisation has announced plans for a vigil in Dr Arday's memory on the steps of the National Gallery in central London at 6pm on Monday.
Prime Minister Andy Burnham on Saturday described the professor's death as a "tragedy on so many levels" and a "really sad, sad and sorry state of affairs".
"It's not a moment for any rushing to judgment. It's a moment for reflection, I would say, reflecting on how things came to this," he told reporters during a trip to Cornwall.
In a resignation letter, Dr Arday had told colleagues: "While criticism is an inevitable part of academic life, what I have experienced has gone far beyond scholarly disagreement.
"The relentless accusations, speculation and public commentary have taken a profound toll on me and on those I love."
He said his resignation shouldn't "be mistaken for an acceptance of the narratives that have surrounded me".
In a statement issued by his publisher Simon & Schuster UK on Friday, Dr Arday's family said he was "subjected to a campaign of sustained abuse" during his tenure at Cambridge "by those who would leave no stone unturned in their quest to undermine him".
Professor Deborah Prentice, vice chancellor at the University of Cambridge, said: "We are desperately saddened to hear this tragic news. Our heartfelt sympathies go to Jason Arday's family and friends at this incredibly difficult time."
The university initially said he was the target of a "vile" smear campaign, but has since launched an independent investigation into his appointment.
The Daily Telegraph reported last month that Dr Arday's thesis contained "more than 100 passages that are identical or nearly identical to a 2009 PhD thesis" by a Brunel University student - although it said he credited the student 17 times.
Liverpool John Moores University previously said it conducted a "confidential procedure" after being notified about the allegations in September, adding that his PhD "still stands".
Dr Arday cancelled promotional events for his memoir, Great And Unfortunate Things, which is due to be published on 27 August.
The publisher had faced calls to postpone its release in the wake of the plagiarism claims and other scrutiny.
Anyone feeling emotionally distressed can call Samaritans for free on 116 123 or visit samaritans.org in the UK. In the US, call the Samaritans branch in your area or 1 (800) 273-TALK.
The Scottish Football Association (SFA) said the Belgian had signed an initial two-year deal that will begin with the upcoming Nations League fixtures.
Pocognoli, 39, previously managed French side Monaco and had a stint with West Bromwich Albion during his playing career.
He said he was "honoured" to get the job and had been "doing a lot of research" on areas the team can build on.
"Along with my coaching staff, I will do everything I can to give them [the fans] a team to be proud of and build on the success that has been achieved already by my predecessor," Pocognoli said.
He added: "We don't have long until the first camp, so the coming weeks will be spent preparing for the UEFA Nations League and putting those plans into action on the training pitch when we meet up next month."
His appointment follows the resignation of Steve Clarke, who led the team to the World Cup for the first time in 28 years but couldn't get them out of the group stages.
The team registered just one goal and one win - against Haiti - in three matches.
Ian Maxwell, the head of the SFA, said he was "delighted" to have Pocognoli in the job, calling him a "very impressive individual, with a real desire to take on the role and a clear vision for how he wants to go about it".
Pocognoli played most of his career in Belgium - his home country - but also spent two seasons with West Bromwich Albion and a season on loan with Brighton in the Championship.
He guided Union Saint-Gilloise (USG) to the Belgian title last year but only lasted eight months at Monaco after a poor run of results at the end of the season saw them miss out on the Champions League.
Managing Scotland is only his third head coach role in senior men's football, but he did manage Belgium's under-16 and under-18 sides.
The first game for the new boss will be the Nations League clash away to Slovenia on 26 September, followed by a home game three days later against Switzerland, and a trip to North Macedonia on 3 October.