The government has established an investigative committee, and two men have been detained for questioning in the April 26 shooting.
Kasper-Ansermet is the second judge to leave the tribunal over the cases, along with a number of important staff members.
Wutty's death provoked outrage from rights groups, who claim the government frequently turns a blind eye to illegal logging.
A former minister of commerce for the Khmer Rouge said soldiers and civil servants of the Lon Nol government were considered “enemies.”
Prime Minister Hun Sen said Tuesday a joint government committee will investigate the shooting.
Shots were fired after a lengthy argument between Chut Wutty and the officials, who appeared to be military policemen.
Saloth Ban, 67, told the court that he had lived in fear of the “terrifying” regime as secretary general of its foreign ministry.
A military police spokesman told local media that officers shot at Wutty, and that one military police officer was killed in the exchang
The men were charged under the new penal code and will face an investigation.
Saloth Ban has been on the stand all week at the UN-backed court describing inner workings of the regime.
Sam Rainsy has been in exile since October 2009.
His testimony corroborates that of convicted torture chief Duch, as prosecutors seek to tie Ieng Sary and two more leaders.