Criminal investigation is a science. If we read the stories of Sherlock Holmes ( which I read when I was a boy, and still enjoy reading), we see how Holmes scientifically solves crimes. Similarly, we see on YouTube how the American police scientifically solves crimes in America, by going to the spot and collecting evidence like fingerprints, bloodstains, fibers, semen, ashes, spent cartridges, etc, which are then sent for forensic examination to a coroner ( in case of a murder ) and laboratories, etc. Modern scientific methods are used e.g. DNA testing, use of national databases for fingerprint testing, etc.
In India, on the other hand, most policemen are not trained in scientific Investigation nor are they provided the equipment or laboratories for it, and yet there is pressure on them, from politicians, their superiors, and the public, to solve the crime, or face some punishment like suspension.
So what does the darogha ( sub inspector ) do ? He often resorts to the time honoured method of torture.
For instance, if a robbery is committed in a village, he enquires who commits such robberies in the area? Someone says Kallu commits such robberies. Poor Kallu is then brought to the police station and given repeated dandas, until he confesses to the crime. Torture is such a terrible thing that one will confess to anything under torture. Joan of Arc confessed to being a witch under torture.
Similarly, when there is a bomb blast in India, the police can never find out and apprehend the real culprits ( because they are nor trained in scientific Investigation), and yet there is pressure on them to solve the crime. So what do they do?
They often announce that some Muslims did it. This is because Muslims in India and elsewhere have been demonised as terrorists and fanatics, who have nothing to do except throw bombs ( though every Muslim I have met was a fine person ).
If a young Muslim gives a fiery speech that atrocities are being committed on Indian Muslims, a CID plain clothes policeman notes down his name, and when a bomb blast occurs, he is implicated, and false evidence manufactured against him.
This is how bomb blast cases are often solved in India