THE POLICE PRESSURE SYNDROME.
Remember that very few police officers are working on just one case at a time. The average murder squad officer might be working on three murders or so whilst he was working on the case you are investigating. There are two points of importance in this - the pressures of work may cause delays but it may also cause mistakes.
And mistakes are what you are looking for.
There is also a common factor in murder cases - and other serious crimes. Consider, if a body is found on a Saturday - a bad day for finding a body because of many uniformed officers are attending football matches. - the murder squad will draft in as many officers as it can find - and as it can afford on overtime.
The Sunday might see a hundred uniformed officers doing "finger-searches" at the scene of crime. There will be a lot of detectives doing door-to-door inquiries too. this is quite a bill, so by the Tuesday or Wednesday the top brass are beginning to question how much this investigation is going to cost. A Commander might well arrive at the scene asking if the number of officers might be cut back. He'll also be complaining about the pressure being put on the force by the Press - and the local people, all of whom are terrified that there could be a second such crime (after all a murderer is on the loose).
Of course, what the police then do depends on on what evidence has already been found - but certain areas of evidence, pathology and scientific - may still not have produced any results. A tug-of-war goes on, but the inevitable cuts have to be made. The Commander always wins.
Now, at this point almost all the evidence will be witness evidence. The questions will have been "When did you last see the victim" ""What he/she wearing" etc - all the questions that you would find on a missing person form. The Commander will ask "do you have any suspects?" . After only three days or so, without the chance to really go through all the files, without the science reports and such, this is rather a stupid question in most cases, but it gets asked.
If the answer is "no", then the Commander will change tack and look at the statistics. It is a fact that historically about 75% of murders are committed either within the family or close friends. So the Commander asks which of this group seems the most likely - and then suggest that that person is brought in for further questioning. That person might even be "put through the ringer."
Now note - if this occurs, then police are basing the case on witness evidence. Many police officer prefer witness evidence anyway - they distrust those clever scientists. Such officers came into the force many years ago - and did burglaries, assaults and such crimes. Their successes in those case were all because of witness evidence, so they like it. Witnesses are pliable - so if an officer is convinced by other evidence that the suspect is guilty, a witness might be persuaded to "shade" his or her evidence as a matter of "public duty". Scientists are often awkward - they let real villains off because of their so-called "professional ethics". Success to them is "truth". Success to the police is "guilty".
You can already see where the mistakes in this kind of scenario lie. In general, scientific evidence is more reliable than witness evidence - and since one of t:
he rules of this game bans you from approaching witnesses anyway, this may well be to your advantage.
Because what happens later in such cases is this:
The suspect is charged on witness evidence.
The science or pathology reports come in. There are elements in them that do not match the suspect - so:
a) the science reports need to be done again and
b) some elements may have to be cut out - or "lost" if the police are not to made to look idiots.
So we need the first ( often called "preliminary" or "interim") science reports and we need to look for physical items taken from the scene which "vanish" from the case, or elements of a normal scientific study that are missing.
Finding "missing items" can often be done by looking for the report of the officer who sent the physical items to the forensic laboratory. He would list those items. When they are returned, they are once again listed, sometimes by the forensic lab, but more often by either the officer carrying them or by the officer who took them back into the productions area. If something is missing, it is missing for a reason.
The above scenario does not apply to every case - because every case is different. You must judge for yourself from whatever you can get - particularly newspaper reports - just what has been going on within the police force. But if you can detect the changes in policy from the general to the specific within the case, you may be able to pinpoint where the police investigation went wrong - and where it is at its weakest.