There are two points. One is that there are elements of the Haitian National Police that take their duties very seriously and elements of the force that are doing the best they can given the circumstances. There is a rogue element of the Haitian National Police force that has used the position for personal gain and has committed human rights abuses, and these continue. The need is there to vet them, and under Security Council resolutions, UN forces have the authority to vet the abusive elements of the national police. It's a question of having the resources and the political will to do it.
So following through on UN Security Council resolutions is one thing. In terms of the culture of impunity, there's a long tradition of impunity in Haiti, and it involves more than just the police sector. It involves actually bringing human rights abusers, both past and present, to trial and ensuring that the court system is able to try them in a fair and equitable manner.
These are not easy things to fix, and they will take time, but they are priorities that have been outlined by the UN. This may not seem like a very satisfactory answer, but it's a question of seeing it through and not settling for expediency or quick fixes.