Gabriel Sitter is a Physics major with a focus in Quantum Physics.  Gabriel's studies led him to join the junior team of the Ghostbusters.
Gabriel was fascinated with the P.K.E. readings given off by the Cerberus Manifestation. Alan Crendall wanted to draw it away from Bridget before they attacked it. Gabriel realized it was gone.
"The technical genius of the group, he's also not scared of getting his hands dirty when the ghosts try and get up close and personal. Following in Dr. Spengler's footsteps, he's keen to learn more about being a Ghostbuster, and make his own mark unearthing more information on the spectral realm and developing his own new technologies." 
- ↑ http://protoncharging.com/gb/2011/02/16/sanctum-of-slime-dev-diary-and-three-new-screens/
- ↑ Level 1 Dialogue
- ↑ http://content.usatoday.com/communities/gamehunters/post/2011/02/first-look-get-to-know-two-more-ghostbusters-rookies/1