An officer with the U.S. special forces says he altered a report about the firefight in which Omar Khadr was captured in order to ensure its accuracy, years after the event.

The senior officer, only known as Lt.-Col. W. due to rules governing U.S. military tribunals, led American troops into the 2002 firefight in Afghanistan.

On Saturday, he testified by video linkup at a pretrial hearing for Khadr in Guantanamo Bay, Cuba.

The 23-year-old Toronto native has been in U.S. custody since he was captured in Afghanistan at the age of 15. Eight years later, Khadr stands accused of throwing a grenade that killed a U.S. soldier.

In a version of the report about the battle written immediately after it took place, Lt.-Col. W. said the person who threw the grenade was killed. In a later version of the report, it says the grenade-thrower lived through the fight.

"The copy that was changed, was for me, for historical purposes," Lt.-Col W. testified to the tribunal, according to The Globe and Mail.

The officer had originally believed that Khadr succumbed to injuries he had incurred in the battle, he said.

Khadr's lawyers have argued that the two versions of the report suggest that military officials were trying to implicate Khadr in the death of the U.S. soldier killed by the grenade.

Earlier this week, CTV News reported that Khadr's lawyers were in talks over a plea deal. If no such deal is struck, Khadr's trial is expected to begin in July.