In 2005, when a team from the Tau'ri visits Chulak in search of Teal'c, they are captured by the forces of the Goa'uld System Lord Apophis. In an attempt to convince Teal'c to join them, they tell him of their origins which he reveals to Apophis when Dr. Daniel Jackson is brought before Apophis for interrogation. Apophis interrogates Daniel for information as the Tau'ri are supposed to possess no Stargate. Ultimately, when Daniel fails to break under torture, Apophis implants him with a Goa'uld to learn all that Daniel knows and then sends the Goa'uld back in the guise of Daniel to act as his spy amongst the Tau'ri.
When the Goa'uld returns to the cell posing as Daniel, the team tells him about the planned breakout with Teal'c's help and he attempts to convince them that Teal'c can't be trusted. As the group prepares to blow their way out of the cell, the Goa'uld is given a gun and nearly shoots Colonel Jack O'Neill, apparently by accident.
As the team approaches the Time Jumper, they meet up with Teal'c who senses the Goa'uld within Daniel and shoots him with a staff weapon, apparently killing him. Teal'c explains that after learning of the threat the Tau'ri poses from the Goa'uld in Daniel. Apophis is now sending a fleet of Ha'tak to destroy the Earth. As they talk, the Goa'uld rises again and kills Airman Jake Bosworth and wounds Teal'c's arm before being shot dead by O'Neill and Major Charles Kawalsky. When he dies, his eyes glow, proving Teal'c's story to the team.
After encountering the Daniel from the original SG-1, the team is forced to tell him that Teal'c killed his other self because he was a Goa'uld. Upon hearing that, Daniel admits that it was a good reason. (SG1: "Moebius, Part 2")
- Previously in the virtual reality simulation of "Avatar", Daniel was a Goa'uld several times as part of the challenge Teal'c had to face. As a result, when the real Daniel entered the simulation to help Teal'c, he was killed by Teal'c under the mistaken belief he was once more the Goa'uld. When Teal'c and Daniel won the simulation though, the Goa'uld was MSgt. Sylvester Siler.