directly attiributable to melanin levels in the the skin?
Most definatly not directly, Indirectly. What i see as the main cause is Belongingness (Yes, a wikipedia link). The definition is "[...] the human emotional need to be an accepted member of a group". The second cause is who you group up with. People tend to group with people of the same culture, status, achievements and race/Skin colour.
As an example, if you would go down to the next bus stop and there are two people of different colour, it is more likely that you will start talking to the one which you feel closer to. A black man would talk to the black man, and white man would probably talk to the person of the same colour. This has nothing to do with racism.
As stated in A Question of Belonging: Race, Social Fit, and Achievement by Gregory M. Walton for Yale University on the belongines by Skin-colour:
"Additionally, they may expect to be socially rejected on the basis of their race [...] in the fear of confirming a negative stereotype about the intelligence of their group. Finally, given the under-representation of their race in academic and professional settings, minority group members may suspect that they would not "fit in" in these settings".
With that in mind, it is safe to see that a black man would join a group of black people before joining one with whiter people, as the chance to fit in is seen as higher in the first group, and since belongingness is a biological trait, it can't be ignored easily. However, this does not mean that the crime-rate goes up, it simply means that the groups become racially divided.
These two charts show average wealth by race and unemployment by race. These two charts in the combination with the crime-rate for race show the corralation between ethnicity and crime.
So yes, colour does mather, as people with with black skin are more likely to commit crime, and if you would become black overnight you would eventually search for belonging in a group of black people, who are statistically more likely to commit crime and live in poverty.
