HYDERABAD: What propels a bullet when trigger of a hand-gun or rifle is pulled? How does a shadow bomb work? Why does a person’s perspiration and breathing change when he lies during a polygraph test? Specialists at Telangana State Forensic Science Laboratory (FSL) explained the answers to these questions, not to trainees but school students of eighth, ninth and tenth standard.
At the Open day conducted on Tuesday to mark Police Commemoration Day, the school students were given a peek into the kind of work that FSL staff are involved in and the kind of cases they deal with.
Experts who work on forensics, ballistics, explosives, forensic biology, narcotics, forged documents and other sections explained how they piece together clues to find culprits and bring out finer details of a crime spoke to the high school students.
Determining parents of children by means of DNA tests, testing deceased blood marks, kind of explosive materials that were used in bombs, Cyber crime cases, and other aspects were explained too.
“A bullet is made up of three parts. Base, Cartridge case and bullet (front portion). When trigger is pulled, hammer hits the base which is high pressure sensitive, which creates a spark. The spark ignites gun powder in cartridge and high amount of gases are released. As gases cannot escape from barrel, they get converted to kinetic energy which push the bullet forward,” said an expert to the school students.
Students were explained how prisoners scribble messages on pieces of paper using sputum or other body fluids which makes the words invisible and how they become visible when exposed to hot air.
“When a person commits suicide by shooting himself, he will be scared and muscles tighten. Because of this, gun will be tightly held in hand. We have to use some force to pull the gun out of hands of the dead person. Also Gun Shot Residue (GSR) will settle on hands. However, if someone else killed the person and planted the gun in the hand of deceased, the GSR will be on the palm of the deceased and the gun can be easily removed. These are the kind of cases we deal with,” said Injeti Venkataiah, joint director of FSL.
An expert who deals with forgery of written notes, documents said that they examine suicide letters to know if it was written by the deceased, if contents are changed in the letter or if someone else has written and planted the letter which would point to murder. They also examine promissory notes, cheques and impersonators writing exams.
“Though deceased had written the suicide note, contents were changed. We dealt with many such cases. For instance, victim of dowry harassment might write a suicide note. However, names in the letter or other contents could be changed,” the expert who did not want to be quoted said.
Students were also explained how Shadow bombs work. “Lets say a bomb is placed in wardrobe. When a target enters room, switches on the light and his shadow falls on the bomb, it explodes” said Sanjeeva Rao, scientific officer and explosives expert at the Foreign Science Laboratory.