This argument doesn't seem to have made much difference to the national DNA database[1]. Innocent people have had to go to court to get the rules changed and to have their DNA taken off the database.

"They" want everyone's dna on the database. And police have said that there's no reason to take a person's DNA off the database.

Your DNA is taken and added to the database if you're arrested. You don't have to accept a caution; nor be tried, nor convicted, of a crime for them to keep it. Some people can apply to have it taken off, but it stays on their for two years for everyone.

With the current climate I can easily see "all immigrants need to go on the database" being populist bit of legislation.

[1] typing that name, about my country, feels weird and wrong.