On air: Is it your duty to help the police ?

26 names are being circulated and they want internet users to work through chatrooms and social networking sites to bring them in.:

Is it in everyone's interests that we help the police ? - does it depend on the crime ? (i.e you might turn a blind eye to some petty theft but not, say, a hit and run accident) or your culture or history ? (no-one likes a "grass" for example) .

Or is catching criminals "their" job ? Why should your risk your safety to help people who are paid to protect you ?