Investigation is a time consuming and expensive police business. It is not as easy as normal trading where commodities are placed in the departmental shops, the police officers just visit the market and buy them. Investigations are sometimes uncommonly complex, intricate and with multiple dimensions.
The parties involved in a criminal case, either in favour or against of it, try to manipulate things in their own ways.
Investigations, in many times depend on some simple analogies. The police are to match the available links with one another and try to find the missing links to form a complete story which would be believable to the court after cross checking.
Interviewing persons related to the incidents or who are the part of the transaction is a major technique of an investigation. The police usually interviews more than one person in this regard. Interviewing 250 people is a big number, but it is not uncommon to go for a spree of interviews or other businesses for the sake of revealing the truth. Not only interviewing related persons or the suspects, but police in overseas take help from DNA tests.
In between 1986 and 1987 while the DNA technology had been at its forming stage the police of East Midland of England, went for a mass screening for the hunt of a rapist-cum-murderer. All male residents between the age of 17 and 34 were requested to voluntarily submit a blood sample. The police tested more than four thousand people and failed to identify the real culprit. They vigourously kept on and succeeded after one year when they tested the 4,583 people, and it was a bakery manager.
In Australia once for an investigation about the rape of an elderly woman in the New South Wales town of Wee Waa, more than 600 male residents volunteered mouth swabs for DNA test.
Oh, our impatient citizens! Try to understand that they are labouring over just to keep you safe and minimise the injustice. In stead of only blaming on them, we should thank them for protecting us as well.