"No external combustible articles were found from the samples collected from the spot (Mantralaya). Our report does not indicate any sabotage in the fire," the officials from the laboratory told PTI.
"The report was submitted to the investigating authority," they added.
Five persons were killed in the ravaging fire that swept through the state secretariat here gutting offices of some of the ministers on June 21.
The city police's Crime Branch, entrusted with the probe into the mishap, has so far recorded the statements of 132 witnesses.
When Joint Police Commissioner (crime branch) Himanshu Roy's comments were sought on the report, he stated, "Inquiry is still on." However, he refused to divulge details further.
The investigators have so far gone through over 100 CCTV footages installed inside the Mantralaya.
Fire broke out on the fourth floor of the seven storeyed building, police said, adding that the switch rack on the fourth floor, from where fire was suspected to have started, had been examined besides other samples that include wood, paper and electrical wiring by the forensic experts.
With the forensic report arrival, a major portion of the police probe is complete, police said, adding that now it will focus on ascertaining if human negligence had caused the fire.
