Pressly shows a disliking to Nihlus when he is onboard before the Eden Prime mission. After Shepard stole back the Normandy, Pressly actually finds the theft as a adventure and continues to work as the navigator until the Ilos mission.
When the team arrives at Ilos, Pressly tells them about detecting Saren's location and argues about the terrain for the Mako to land on. He helps the crew on the Normandy during the Battle for the Citadel.
Mass Effect 2Edit
After one month of Sovereign's attack on the Citadel, the crew is sent to search for Geth activity. Pressly believes that there are no geth but that the slavers are the problem. While searching a Collector ship attack the Normandy.
Pressly is the first crewmember to get killed in the attack. A explosion cause him to be knocked out, meaning he died when the Normandy crashed.
If Shepard visits the Normandy crash site, they can find Pressly's datapad.
Mass Effect 3Edit
He's name is present on the memorial wall.