The Army on Wednesday launched an independent investigation into the firing in which 13-year-old Dilson of Indira Gandhi Nagar here was killed in a defence residential complex on July 3.

Two top-ranking officers inspected the scene of crime and made enquiries with the General Officer Commanding and others, Army sources said.

In a separate development, the Crime Branch CID police, investigating the case, conducted a thorough search of the defence residential complex in a bid to seize the weapon used to commit the crime.

“Preliminary enquiries revealed that the bullet fired was most probably from the high-calibre rifle and from a close range. The bullet pierced through the victim's head and hit a wall, partly damaging it. The impact on the wall and the make of the bullet indicate that an assault rifle was used,” a senior police official said.

After analysing the stock of arms and ammunition in their armoury, Army officials examined licensed weapons in the possession of individuals on the campus. “Licensed weapons are also kept in the armoury. We cannot rule out the possibility of the shot being fired from an unlicensed weapon. A detailed investigation is on to apprehend the person involved,” an Army official said. There was no instruction given to any sentry to open fire at trespassers.

“It is a residential complex where there is nothing classified. We have only asked guards to intercept intruders and make enquiries about their presence in the area,” he said.

Expressing concern over “false” reports published in a section of the media, Brigadier (Administration) Sashi Nair said the Army was extending full cooperation to the investigating agency (CBCID) and would leave no stone unturned in its endeavour to apprehend the accused. “There is no question of defending anybody. We are viewing this very seriously…it involves the reputation of the Army. The General Officer Commanding has written to Tamil Nadu Chief Secretary Debendranath Sarangi assuring expeditious investigation in the case,” Brigadier Nair said.