The Police said that Emil Ranjan was arrested over the deaths of several inmates at the prison during the prison riot in 2012.
Earlier, an Inspector of the Police Narcotics Bureau (PNB), Neomal Rangajeeva was also arrested over the deaths of several inmates during the 2012 Welikada prison riots.
Emil Ranjan and the inspector were remanded till April 10th.
The riot in 2012 left 27 inmates dead and several injured. The riot broke out during a search for illegal arms.
The Government had appointed a committee to investigate the riot and a report was compiled on the incident.
In January last year the Human Rights Commission in Sri Lanka (HRCSL) recorded a statement from a journalist over the riot.
The statement was recorded from journalist Kasun Pussewela after he had filed a petition at the HRCSL.
Pussewela had sought an investigation into the incident saying there was ample evidence to prosecute some people who were responsible for killing prisoners who took part in the riot.
The HRCSL obtained written evidence from Pussewela as well as video and photographic evidence. (Colombo Gazette)