ALEXANDRIA, Va. (AP) — An Army general who investigated the abuse of prisoners 20 years ago at Iraq’s infamous Abu Ghraib prison testified Tuesday that a civilian contractor instructed prison guards to “soften up” detainees for interrogations.

The retired general, Antonio Taguba, told jurors that the contractor, Steven Stefanowicz, even tried to intimidate the general as he investigated the Abu Ghraib abuses.

“He would lean on the table staring me down. He did not answer questions directly,” Taguba said. “He was trying to intimidate me.”

Taguba’s testimony was the strongest evidence yet that civilian employees of the Virginia-based military contractor CACI played a role in the abuse of Abu Ghraib inmates.

Three former inmates at the prison are suing CACI in federal court in Alexandria, alleging that the company contributed to the tortuous treatment they suffered. The trial, delayed by more than 15 years of legal wrangling, is the first time that Abu Ghraib inmates have been able to bring a civil case in front of a U.S. jury.