The accused in the Mumbai gangrape case have admitted to having earlier committed two rapes and a molestation inside the deserted Shakti Mills compound, investigators said on Tuesday.
As forensic experts scoured the mill compound for more evidence, the accused were subjected to a Layered Voice Analysis (LVA) test, which is designed for truth verification and detection of deceit.
LVA helps measure the emotional content of human speech, captured live or extracted from recorded audio.
During interrogation, the accused admitted to having raped a ragpicker and a sex worker on separate occasions a few months back, said a crime branch official privy to the probe.
"However, so far no complaints have been received as regards the above incidents.
"Also, there appears to be a molestation of a woman, who had come to the defunct mill with her partner," the official said, adding that such incidents as could have occurred over the last six months were being verified.
Speaking on condition of anonymity, the officer said that they have identified another key witness in the gangrape of the 23-year-old photojournalist.
The victim, an intern with an English magazine, was allegedly raped by the five accused when she had gone on an assignment to the desolate Shakti Mills premises on August 22 accompanied by a male colleague. The colleague is a prime witness in the case.
All five accused — Salim Ansari, Vijay Jadhav, Chand Babu Sattar Shaikh, Mohd Kasim Hafiz Shaikh alias Kasim Bengali and Siraj Rehman Khan — have been arrested and are in the custody of Crime Branch.
The officer said that when Salim made a phone call to Kasim on the day of the crime, asking him to immediately reach Shakti Mills, the latter was present in a shanty with Chand, Siraj and one more person.
"That person has been found and made a witness in the case," he said.
Earlier today, two teams from the Central Forensic Science Laboratory, Delhi, and Gujarat Forensic Science Laboratory thoroughly examined the crime scene for nearly three hours to gather evidence for a watertight case against the accused.
The team from Gujarat comprised two psychiatrists who conducted the LVA on the accused.
The Crime Branch has, meanwhile, decided to conduct a bone ossification test to ascertain the age of Chand Shaikh in order to disprove his family's claim that he was a minor aged 16 years.
"Chand was involved in a theft case in 2011. Going by his previous criminal record, he should be a major now.
"However, we do not want to take any chances. To make it a watertight case, we have decided to conduct ossification test on Chand," the officer said.
According to police, the four other accused are above 20 years of age.
Police have also conducted searches at the homes of the accused and recovered clothing, including undergarments.
The officer said that the victim was forced to clean the crime scene after the rape, but added that plenty of evidence was still collected from the spot.