Guwahati, March 22: Investigation into the Bandana Kalita gang rape and murder case could be delayed because the chemicals required for forensic tests are unavailable in the laboratory here.

Police had yesterday sent the clothes of the victim and the three accused to the laboratory for matching the body fluids. These were to be produced in court as evidence. However, the laboratory returned the samples citing a lack of required chemicals.

"The rape can be established during post-mortem and some other medical examinations but matching of the body fluids is a clinching evidence in the court along with the chargesheet. But since the forensic laboratory does not have the facility at present, we have decided to send the samples to Central Forensic Science Laboratory in Calcutta," deputy commissioner of police (Guwahati Central) Ranjan Bhuyan said.

Sources, however, said it would delay the investigation as the process of sending the samples to the laboratory in Calcutta might take time. "They (CFSL) have many cases. This is definitely going to delay the process in submitting strong evidence in the court for trial," a source said.

Three persons - Dimbeswar Das, 31, Joy Ram Hazarika, 42, and Shyam Charan Pathak, 40 - were arrested yesterday for allegedly gangraping and murdering 22-year-old Kalita, the daughter of a colleague at Noonmati here on March 15. Police said the trio had confessed to the crime. They pounced on the girl at Noonmati Sector 1 when she was returning home after attending an interview.

The victim's body was found inside a jungle close to her residence on March 17. Her father and the three accused are casual workers at the IOC refinery in Noonmati.

The prime accused, Das, had even taken part in a protest against the incident on Thursday. Pathak left for his father-in-law's house in Nalbari and did not return, though his mother was ill. This made the police suspicious. "When he came back yesterday, we questioned him and found a cut on his left hand which turned out to be a teeth mark of the victim during the struggle," a police officer said. The trio are in police remand for interrogation.

Officials of the forensic science laboratory at Kahilipara told The Telegraph today that they had not been able to conduct the tests owing to a lack of the required chemicals for the past year. "Normally, body fluids are extracted from the clothes and are matched with the use of some chemicals. Since we don't have the chemicals, we are unable to conduct the tests. We had written to the home department but we have not received them yet. These chemicals are very costly and five grams of such a chemical costs more than Rs 2 lakh," said a senior official.

Set up in 1967, the laboratory, which offers services to police in Assam and parts of the Northeast, has often faced problems of necessary facilities, including equipment and chemicals.