Spokesman and minister Rajitha Senaratne said the newly-elected government of President Maithripala Sirisena will open up the murders cases which took pace during the regime of his controversial predecessor.
These include the murders of Nadaraja Raviraj, a Tamil MP from Jaffna, Joseph Pararajasingham, another Tamil MP from the eastern province, Lasantha Wickrematunga, the editor of the Sunday Leader newspaper and Jeyaraj Fernandopulle, a former Rajapaksa minister.
"We know who did them, we have all the information," Senaratne said.
Wickrematunga, the editor of the pro-opposition Sunday Leader was murdered after he ran a series of anti-Rajapaksa articles.
The investigations on all these were stalled or abandoned without credible conclusions.
The Sri Lankan military finally crushed the LTTE militants in May 2009, ending the 30-year civil war fought for an independent state for ethnic minority Tamils. The UN says between 80,000 to 100,000 people were killed in the brutal conflict.