"He was very puzzled over completion of an investigation relating to the Maoist-security forces encounter in Palamu for the last couple of weeks," said KS Meena, additional director general of police (ADG), CID.
Family members corroborated it and added that Maitra was not in a good health and was tensed even at home over official issues.
A close friend of Maitra revealed that an ASP rank officer had recently called him and warned him to wind up Palamu encounter probe before his retirement, which was due in July this year.
"Maitra had confessed to me that he had erred in his task and was unable to rectify it," the friend told HT at the DSP's residence.
He is survived by his wife and two children. His children study in Bangalore and were informed about the incident.
After an autopsy, the DSP's body was taken to CID headquarters at Rani Kothi where he was accorded a ceremonial guard of honour. The last rites would be conducted only after the children reach.
As per official sources, the DSP was handling investigations of at least four important cases including the Palamu encounter. Maoists had planted explosives inside a slain jawan's body in the incident.