How on earth do you know they don't have genuine concerns?These people have precisely zero "genuine concerns". They are prejudiced against them simply because they are migrants.
Remind me of what nationality the likes of Sutcliffe and Huntley were. Plenty of bad native English people.
Personally I'm sick to the back teeth of people whinging and whining about migrants.
Why would they protest and raise their concerns about past serial killers that are now dead?