What helicopter does the US Customs and Border Protection use?
I think you are going to be in for a rude wakening in that since the U.S. customs and Boarder parole fly unarmed helicopters they can fly anything from Robinson 44s to Black Hawk Helicopters depending upon whats available. They can even rent a helicopter if they have a need so your not going to be able to look up and directly identify them. Add to the mix news media, County and City patrol craft, Search and rescue, Military patrols and life flight hospital flights and you are not really going to separate one from the other.