For about 30 years, Halloween was taken over by pranksters. By the '30s, pranks were causing cities millions of dollars of damage. They considered banning Halloween in many cities, but instead, parents got together and came up with party ideas for kids, and a lot of them involved dressing up and costuming.
The main difference is, in 'Cold Case,' the victim sometimes had been dead for decades - you didn't have the advantage of being able to interview the victim. You had to piece together the circumstances surrounding the crime from witnesses and other evidence. 'SVU' is much more immediate in that you can talk to the victim.