The official was identified as T.J. Jose, the inspector general of police of Thrissur range.
Jose told the media that he had done no wrong and left the examination hall at 11.30 a.m. on his own. The exam was due from 10.00 a.m. to 1 p.m.
"I have done nothing wrong and I will return for the last examination tomorrow," he said.
The invigilator who caught Jose cheating was unaware of his identity, said an informed source.
Director General of Police K.N. Balasubramanian said action would be taken against Jose. Additional Director General of Police Shankar Reddy has been asked to prepare a report.