Two other Czech soldiers were wounded in the attack, which took place at Shindand air base in western Afghanistan’s Herat province, according to a press release after the incident.
According to The New York Times, the attacker was arrested within hours by Afghan forces. They then transferred him to NATO custody.
When he was returned to Afghan custody later that night, he had been severely beaten and was unconscious.
He died a short time later, Afghan officials told The Times.
U.S. Army Criminal Investigation Command confirmed to Army Times that it is conducting an investigation into the incident.
However, the command wouldn’t provide additional information in order “to protect the integrity of the ongoing investigation," an Army CID official said in an email.
The New York Times reported that Czech soldiers are also under investigation relating to the Afghan commando’s death. Jan Pejsek, a spokesman for the Czech Ministry of Defense, said in an email to The New York Times that “we strongly deny any such accusations" and cited an ongoing investigation into the insider attack.
U.S. officials said American leadership in Afghanistan sparked the Army CID investigation.
“Gen. Miller, the commander of NATO’s Resolute Support Mission, requested the U.S. Army Criminal Investigation Division conduct an investigation into the facts and circumstances surrounding the death of the shooter,” U.S. Army Maj. Bariki Mallya, a spokesperson for NATO troops, told Army Times.
“CID will investigate to determine whether any potential misconduct occurred, and we will hold individuals accountable, as appropriate," Mallya added.
Cpl. Tomáš Procházka was mortally wounded by an insider attack on his vehicle in Afghanistan in October 2018. (Czech Army)
Mallya would not confirm the status of the troops being investigated, whether it involved only U.S. soldiers or whether the troops are still operating in-country.
Insider attacks, in which an individual in an Afghan police or military uniform uses his weapon on coalition troops, have long been a part of the war in Afghanistan.
These types of attacks decreased after the troop presence was scaled back in 2015, when the mission shifted to a predominantly advise and assist role.
This year has been particularly brutal for insider attacks, however.
Gen. Scott Miller, the top U.S. commander in Afghanistan, was present during an Oct. 18 insider attack that left a key Afghan general dead and wounded an American one-star general.
In September, the senior enlisted soldier of 3rd Squadron, 1st Security Force Assistance Brigade was killed in an insider attack.
There have been four insider attacks in 2018, according to archived press releases on NATO’s Resolute Support website. That is compared to no insider attacks in 2017, one in 2016 and two in 2015, the year the Resolute Support mission began.
In September, U.S. Defense Secretary Jim Mattis said the Afghan military has increased its vetting of local forces working with American troops after the spate of insider attacks over the summer.
The increased security checks for Afghan forces will “make certain we’re catching people who have been radicalized,” Mattis told reporters at the Pentagon.
“And there’s a lot of attention from their military side that’s actually in the field with the troops,” he added. “And by ‘attention,’ I mean training of their people on how they protect the coalition troops.”