When multiple cultures mix together, one of two things can happen:
The cultures mesh well and either coexist or mutually mix into something new
The cultures do not mesh well and this leads to all sorts of problems, especially increased crime
The second usually happens when both cultures place opposite value in something. For example, one culture places a high value on self and the other places a high value on being in a group, this can lead to a divide between cultures. Eventually, the resentment each group has for each other will lead to violence and other sorts of crime. One culture may think “I made the money for myself,” while the other thinks ,“we should all share the money.” If people don’t learn how to get along, you can probably see how that would increase criminal activity. In most cases, it is usually the expectation that the immigrant adapt to the culture of the new place they have moved to, rather than the new place’s home residents being expected to adapt to every immigrants different country cultures.
It also isn’t good when immigrants enter a new country and do not know the laws of the country they have entered. They may commit crimes that could have been legal wherever they came from, but now someone may be a victim to a crime and the immigrant did not know. Now, usually immigrants that legally enter a country do learn about the basic laws of the country and the basic culture, but ones that enter a country illegally may know nothing about the place they are in. They may continue to act the same as they did in their previous home, which may have very different laws, leading to further divide.