When accused Congolese militia leader Thomas Lubanga saw the prosecution’s next witness walk into the courtroom on Wednesday, he leaned forward in his chair and covered his face with his hands.

A moment later, he abruptly stood up and appeared to be patting his eyes with a white handkerchief. He was then led out of the room by security guards.

Court immediately adjourned so Lubanga could meet with his lawyers and the unnamed witness could provide the court with his identifying details.

It is unclear what provoked the defendant’s reaction, who until now has displayed little to no emotion in the courtroom.

Judge Adrian Fulford told that court only that Lubanga and the witness have “been aware of each other for years.”

This witness, identified only by the number 41, will be the fourth to testify in the trial of the accused militia leader. Lubanga is charged with conscripting and using child soldiers to fight in his militia in the ethnic conflicts that raged in the Ituri region in the Democratic Republic of Congo during 2002 and 2003.

The defense concluded on Wednesday its cross-examination of the former child soldier who originally recanted his testimony. Most of it was conducted in closed session.