Updated

A key prosecution witness has begun testifying in the federal trial of three Minnesota men accused of plotting to travel to Syria to join the Islamic State group.

Twenty-year-old Abdullahi Yusuf took the stand Friday to testify against what he called his three "former friends."

Yusuf is among those who have pleaded guilty. The Star Tribune reports he testified that he intended to leave the U.S. and fight alongside Islamic militants in the Middle East. Yusuf says he chose to cooperate with the government because what he was doing "was not right."

Minnesota Public Radio News reports he admitted Friday that even after he agreed to cooperate with the government, he withheld information.

All three defendants have pleaded not guilty to multiple charges.