1058 GMT March 31, 2020
Suu Kyi was speaking at a memorial service organized by her ruling National League for Democracy (NLD) party in Yangon on Sunday.
Ko Ni, a prominent critic of the military's continued political influence, was shot dead on January 29 outside Yangon. A taxi driver was also killed attempting to stop the gunman.
Authorities say the gunman was hired by a former military officer who is now on the run.
Myanmar’s de facto leader also described both Ko Ni and the taxi driver as "martyrs."
"Losing U Ko Ni is a great loss for our NLD. He worked together with us for many years through his beliefs," Suu Kyi said.
Ko Ni was opposed to the military’s control of key security ministries and guaranteed seats in parliament. He had also denounced the increasing Islamophobia that has swept through the country in recent years.
Suu Kyi's NLD has already branded the killing a political assassination and "terrorist act."
At the Sunday memorial, Suu Kyi did appeal for patience, arguing that her government had only been in power for 10 months after decades of junta rule.
"Our citizens who have been struggling hard for many decades may think it's a very long time. But for the history of a country, for the history of a government, 10 months or one year is not much. This is just a short period," she said.
Suu Kyi, a Nobel peace prize laureate who has been lionized in Western media as Myanmar’s “democracy icon,” has defended the military's crackdown on Rohingya Muslims in Rakhine state, much to the dismay of the international community.
Rakhine has been under a military siege since October 2016 over a raid on a police post that was blamed on the Rohingya. There have been reports of rape, murder, and arson against the Muslim population in the state.
Suu Kyi, however, has described the crisis in Rakhine as “under control” and demanded that the international community stop stoking the “fires of resentment.”
The bloody crackdown on the Muslims by the military has posed the biggest challenge to Suu Kyi since her NLD party won Myanmar’s first democratic elections in a generation in late 2015.