A CISF head constable killed himself with his service revolver at the National Human Rights Commission building here on Saturday, an official said.
S. Raja Manikam, 47, shot himself around 7.50 p.m., said an official of the Central Industrial Security Force.
The head constable was posted at the NHRC office in central Delhi.
Manikam had returned from a 29-day leave earlier this month and was facing health problems, the official said.
Senior officers of the CISF reached the spot, and police were also informed.