Well I'm not from Sweden so I cannot comment on that, but it's a well-known and documented fact that e.g. here in the Netherlands, ethnicities other than 'Dutch' are over-represented in about every negative statistic that is being tracked, amongst which are crime statistics. I could point you to cbs statline, which is the goverment statistics body, but it's in Dutch so I don't know if it's of any use to you, see [1] and particularly [2] for an overview table of crime statistics grouped by native, non-native, non-native+non-western, etc.

Whether these groups are over-represented because of socio-economic status, cultural factors, genetics or whatever seems largely irrelevant to me if you ask me, especially if you are reasoning about immigration in the context of public safety. None of these factors are controllable, and typically immigrants from distressed countries will both fall in the 'different culture' and 'low economic status' category at the same time. For public safety, the root cause why they are over-represented in 'bad lists' seems irrelevant to me.

Let's be clear that I don't mean to pass judgement on immigration policy, just pointing out that if you are creative with statistics you can prove or disprove almost anything to be related to everything, depending on your agenda. Correcting a statistic 'immigrants are over-represented in crime statistics' by saying 'but not compared to swedes with low economic status' seems like a pretty desperate attempt to paper over the fact that accepting large number of immigrants will not improve public safety, so to say.

[1] http://statline.cbs.nl/Statweb/

[2] http://statline.cbs.nl/StatWeb/publication/?DM=SLNL&PA=81947...