[swede123]

Your question doesn't have a clear-cut answer. It depends on the profile of the victim, unusual circumstances of the crime, which jurisdiction is involved, socio-economic factors relating to the crime scene and so on.

To give you a real-world example. In 1986 Olof Palme, Sweden's prime minister was murdered on a Stockholm street. Initially there were literally hundreds of Swedish police officers working on the case, quite the manpower allocation for a small country. Some suspects were apprehended, but no one was conclusively found guilty. The case has remained in a semi-active state with Swedish police interviewing people as recently as 2001, once again finding no conclusive evidence of anything. In summary, the prime minister was murdered and the case became dormant after three or four years. Now imagine some random drug dealer or what not being gunned down. I imagine this investigation wouldn't last much more than a few months.

Swede