The former Chief Constable of West Midlands Police has warned that quitting the European Union would make it harder to fight crime.
A vote for Brexit would help international criminals escape justice and create “a serious gap in our security arrangements, said Chris Sims.
The top cop led West Midlands Police, the largest force outside London, for more than six years before retiring in December 2015.
And speaking out as the nation prepares to vote in Thursday’s referendum , he warned that exiting the EU would make the region less safe.
He highlighted a Birmingham-based operation called Trivium which saw police from across Europe working together.
Mr Sims said: “The crime threats we face are becoming increasingly global.
“That’s why operations like Trivium, which draw on European cooperation are so important.
Below: The EU referendum explained
“While it would be misleading to suggest that a Brexit would be the end of joint working I have seen nothing in this campaign to suggest that the same level of cooperation could survive were we to leave the EU, creating a serious gap in our security arrangements.”
Read more: The Birmingham Mail backs Remain
Operation Trivium has become a regular event as police from different countries come together to crack down on foreign crooks operating or taking shelter on these shores.
The latest one, in May this year, saw West Midlands Police working with continental police and UK partner agencies from a headquarters in Edgbaston, Birmingham.
Below: Police carry out raids on suspected criminals
Officers from Romania, Lithuania and Holland were involved along with a Finnish officer representing Europol, the European police force.
And officers across the country stopped more than 9,000 vehicles – 509 of which were seized – and made 361 arrests.
A total of 83 people, including 76 foreign nationals, were arrested in the West Midlands region alone.
They included Polish national Marian Andraczek (44) picked up at an address in Maple Grove, Lozells, over fraud offences in his home country.
Czech burglar Ladislav Mikusiak (62) was arrested from a car on the M5 while 32-year-old Jacek Wisniewski – wanted by fraud detectives in Poland – was detained by West Midlands Police officers working at a warehouse in Coventry.
All three were detained under European Arrest Warrants, allowing them to be deported to face justice.
Labour Shadow Police Minister Jack Dromey (Lab Birmingham Erdington) said: "As the Chief Constable of Britain's biggest police force outside of London, no one is better placed to point to the dangers that Brexit will expose the British people to."
As the EU fight continued, Labour sent out every living former party leader, along with current leader Jeremy Corbyn, to make the case for remain.
Ed Miliband, who led Labour in the last general election, and Harriet Harman, who was acting leader following the election, were in Birmingham.
Former Prime Minister Gordon Brown was in Glasgow. Neil Kinnock, who led the party in the 1980s and early 1990s, was in Cardiff. Margaret Beckett, a former acting leader, was in Derby.
Mr Corbyn spoke in Manchester, where he was expected to argue that a vote for the EU was a vote for “jobs and rights at work”.
Watch: Jeremy Clarkson and James May give their views on the EU Referendum
