Police to arrest cyclists?

On Jul 30, 11:59*pm, "Zapp Brannigan" wrote:


But perhaps no charges will be brought in the end, after all they've had a
useful educational experience and their DNA etc is now on record to deter
future misconduct. * It's a win-win scenario for the Babylon (and a terrible
own goal by the fanatics who tried to disrupt our Olympic opening ceremony).

Why is their DNA held, I understood the DNA of those arrested but not
convicted or proceeded against would be removed from the database? I
hope this an automatic process or is it something the arrested person
has to instigate himself?