The truck driver arrested after 39 people died in a lorry's refrigerated trailer is a Northern Irishman who calls the vehicle he drives 'the polar express'.
Mo Robinson, 25, is at the centre of one of Britain's biggest ever murder investigations after an ambulance crew discovered the bodies in his trailer after he pulled up near the Dartford Crossing in Essex last night.
Robinson, who is from a small village near Portadown, Northern Ireland, regularly posts about the Bulgarian-registered Scania truck on his Instagram and Facebook pages, referring to it as 'the Scandinavian Express' and 'the Polar Express'.
Social media posts suggest Robinson makes frequent trips to Denmark and Sweden, which would require driving through Britain.
The deaths will lead to renewed calls for added checks on vehicles entering Britain through so-called 'soft spot' ports, with Border Force resources currently focused on Dover.
The fact that the lorry arrived at Holyhead on Saturday suggests those who died may have been in the back of the vehicle for at least four days.
A member of the Freight Transport Association (FTA) said the lorry could have got a ferry from France to Ireland, then driven through Ireland before boarding another boat to Britain.
Seamus Leheny said: 'If the lorry came from Bulgaria, getting into Britain via Holyhead is an unorthodox route.
'People have been saying that security and checks have been increased at places like Dover and Calais, so it might be seen as an easier way to get in by going from Cherbourg or Roscoff, over to Rosslare, then up the road to Dublin. It's a long way around and it'll add an extra day to the journey.'
A source told the Irish Daily Mirror they believed the container first arrived in Belfast, before it was taken down to Dublin and then on the ferry to Holyhead.
The lorry's trailer is understood to be refrigerated, meaning temperatures inside could have been as low as -25C.
Describing the conditions inside, Road Haulage Association chief executive Richard Burnett said, if the was refrigerated was switched on, conditions inside would have been 'absolutely horrendous' and would kill anyone inside 'pretty quickly'.
Mr Burnett added: 'It's going to be dark. If the fridge is running it's going to be incredibly cold.
'The only place to go to the toilet is on board the back of the trailer. You can imagine if they've been in there for days then there will be faeces, there will be urine.'
Prime Minister Boris Johnson has said he is 'appalled' by the tragedy and that his thoughts are with those who lost their lives and their loved ones.
He tweeted: 'I'm appalled by this tragic incident in Essex. I am receiving regular updates and the Home Office will work closely with Essex Police as we establish exactly what has happened. My thoughts are with all those who lost their lives & their loved ones.'
During Prime Minister's Questions in the House of Commons, Thurrock MP Jackie Doyle-Price said: 'To put 39 people into a locked metal container shows a contempt for human life that is evil. The best thing we can do in memory of those victims is to find the perpetrators and bring them to justice.'
Responding, Boris Johnson said: 'It is hard to put ourselves in the shoes of those emergency services, as the right gentleman opposite (Jeremy Corbyn) said, as they were asked to open that container and to expose the appalling crime that had taken place.
'I must say I do share her strong desire now for the perpetrators of that crime, and indeed all those who engage in similar activity - because we know that this trade is going on - all such traders in human beings should be hunted down and brought to justice.'
Irish premier Leo Varadkar said any necessary investigations would be undertaken if it was established the lorry had passed through Ireland.
'The information that we have so far this morning is very sketchy but there are some reports that the truck may have passed through Ireland at some point,' he told the Dail parliament in Dublin.
It is the biggest disaster of its kind since 2000, when 58 Chinese stowaways died on a ferry from Belgium to Britain.
Today's tragedy has claimed more victims than the Manchester Arena bombing, in which 22 were killed.
In 2015, 71 migrants, including eight women and four children, were found dead in the back of a Slovakian meat lorry which was abandoned truck on an Austrian motorway.
The industrial estate where the lorry was found today is next to the Dartford Crossing and is used as a stopping point for lorries travelling south to the Port of Dover and the Channel Tunnel, although the planned route of the lorry involved is unknown.
Lithuanian lorry driver Tadas Cesnavicius works in the area.
The 40-year-old said: 'You see a lot of lorries coming in and out the area, but whether they have people inside who knows?
'It is terrible to hear it happened right in the next road.'
Emergency services sent five ambulances, their hazardous area response teams and a car from the Essex and Herts Air Ambulance to the scene.
A restaurant worker in the industrial estate said the area was cordoned off by police this morning.
'There's a lot of police and forensics,' the Big Blue Food Bus employee said. 'It's awful. We thought maybe someone had broken into a lorry, but it's just awful.'
Essex Police said it set up a casualty bureau for people to call if they are concerned about relatives following the incident at the industrial park in Grays.
Essex Police Chief Superintendent Andrew Mariner said: 'This is a tragic incident where a large number of people have lost their lives. Our enquiries are ongoing to establish what has happened.
'We are in the process of identifying the victims, however I anticipate that this could be a lengthy process.
'We believe the lorry is from Bulgaria and entered the country at Holyhead on Saturday, October 19 and we are working closely with our partners to investigate.
'We have arrested the lorry driver in connection with the incident who remains in police custody as our enquiries continue.'
The investigation will now try to work out where the people came from and what route they had taken to get to the UK.
Alp Mehmet, the chairman of the group Migration Watch UK, called on the government to better patrol Britain's borders to ensure such tragedies were not repeated.
He said: 'People-trafficking is a sickening business. It continues not only because the traffickers make huge amounts of money from it but are also often able to get away with it.
'The risk is that more such tragedies will occur for so long as the UK fails to properly resource the border and return those who have no right to be here, which all but encourages traffickers to ply their trade by exploiting people who put their lives in their evil hands.'
Despite the investigation being at an early stage and it being unclear where the victims died, the Joint Council for the Welfare of Immigrants has already blamed the British government.
The charity's chief executive Satbir Singh said: 'Nobody should be in any doubt that the ultimate responsibility for these deaths lies with government policy which has deliberately closed down safe and legal routes into Britain.'
Bulgarian foreign ministry spokesman Tsvetana Krasteva said: 'We are in contact with our embassy in London and with British authorities.'
The National Crime Agency (NCA) said: 'We are aware of this tragic incident which is now the subject of a murder investigation being led by Essex Police and we have deployed NCA officers to assist.
'We are working with partners including Essex Police and Immigration Enforcement to provide specialist support to urgently identify and take action against any organised crime groups who might have played a role in causing these deaths.'
The Essex Police casualty bureau numbers are 0800 056 0944 for callers living in the UK, or 0207 158 0010 for people dialling from outside the UK, the force said.