PUNE, Jan 31 (TOI) : A 25-year-old engineer was strangled with a computer cable on the premises of software major Infosys here late Sunday night. A security guard was arrested for the killing, police said on Monday.

Rasila Raju O P was found dead in the conference room of the 9th floor office of Infosys in Phase II of Rajiv Gandhi Infotech Park here. The systems engineer, from Kozhikode, Kerala, was working on her day off. Footage from CCTV cameras on the campus helped police track the guard. A court remanded the accused, Bhaben Saikia, in police custody till February 4 after police nabbed him at Chhatrapati Shivaji Terminus in Mumbai.

An officer said Saikia, 27, who is from Assam, told cops Rasila had reprimanded him for "staring" at her, and threatened to complain to authorities. "Rasila came to the office at 2pm on Sunday and was working in a section on the ninth floor while her two teammates were working online (with her) from Bangalore," said deputy commissioner of police Ganesh Shinde.

Saikia allegedly entered the section on the pretext of noting down serial numbers of some computers. "He then asked her not to complain against him for his actions," Shinde said, quoting Saikia. Later, another guard saw her body lying on the floor and alerted the authorities, cops said. Rasila was rushed to a hospital where she was declared dead.

The cameras on the ninth floor recorded Saikia following Rasila to the restricted area where she worked. "Rasila used her ID-cum-access card to enter the restricted area and Saikia followed her," Shinde said. He left the door open so that he could enter and exit at will. Rasila was working all alone in the office, police said.

The company officials told police that barring employees, no one was allowed in this section of the floor. "Rasila may have left her cubicle and gone to answer a phone call in the conference room located within the restricted area, when Saikia entered the room once again after 5pm," Shinde added. The footage shows Saikia running away from the restricted area around 7pm. "He was the last person spotted in the area and we used the 'the last-seen theory' to solve the case.

After Saikia left the floor, Rasila stopped communicating with the Bengaluru team," police said adding that Saikia's cellphone location showed that he was heading towards Mumbai. After Rasila stopped responding to the Bengaluru team, they waited for an hour after 7pm and then informed the Hinjewadi office. An employee went to the ninth floor around 8.30pm and found Rasila lying on the floor.