For an undisclosed amount of time, Holtzmann and Abby Yates worked on a prototype Proton Grenade while they were employed at the Kenneth P. Higgins Institute. When Erin Gilbert was fired from Columbia University for her involvement in the investigation of Aldridge Mansion Museum, she returned to the Institute. She shared the news, angrily threw her purse down, and threatened to throw the prototype grenade at them. She wasn't aware of what she had in her hand, but Abby and Holtzmann were quite aware and talked her into putting it back down on a pile of components. Abby instructed her to put it down carefully. Erin slammed it down. Abby and Holtzmann were spooked. Holtzmann described it as having the capacity to turn everyone in the room to ash from the inside out. It was later seen briefly on the table Erin and Abby sat at when they told Patty and Holtzmann how they first met. From the prototype she perfected the Proton Grenade (Air Filter) and the Proton Grenade (Test Tubes); both of which were used in the Times Square battle.
- ↑ Holder, Nancy (July 2016). Ghostbusters, p. 137. Tom Doherty Associates, LLC, New York NY USA, ISBN 076538843X. Narrator says: "Now Erin recognized the object--the grenade shape, the folded material in the center that looked like an air filter."
- ↑ Abby Yates (2016). Ghostbusters (2016 Movie) Extended Edition; Chapter 4 (2016) (Blu-Ray ts. 00:23:11-00:23:13). Sony Pictures. Abby Yates says: "No! God, no! We will all die."
- ↑ Jillian Holtzmann (2016). Ghostbusters (2016 Movie) Extended Edition; Chapter 4 (2016) (Blu-Ray ts. 00:23:13-00:23:15). Sony Pictures. Jillian Holtzmann says: "Turn to ash from the inside out."