Lasantha Wickrematunga was killed in broad daylight in January 2009 when some unidentified bike-borne assailants gunned him down in the Colombo suburb of Ratmalana.
He was the founder and editor of The Sunday Leader, and was involved in a legal fight with Rajapaksa's brother, the then powerful defense secretary Gotabaya Rajapaksa.
After a decade-long rule of Rajapaksa was ended in 2015, the new government under President Maithripala Sirisena has revived the murder investigation.
Wickrematunga was declared a World Press Freedom Hero of the International Press Institute in 2010.
In his final editorial which was published in 2009 after his assassination, Wickrematunge wrote, "When finally I am killed, it will be the government that kills me."
He also wrote that he hoped his murder would not be interpreted as a "defeat of press freedom but as an inspiration".