|“||Open the door and you'll find me.||”|
— Kerry's hint to Strahm and Perez[src]
Before her death, Detective Allison Kerry kept in contact with special agents Lindsey Perez and Peter Strahm, giving them the info she had obtained concerning the Jigsaw case. In Kerry's last message, she had informed them that two officers might be in danger, while supplying the agents with a key and another hint. Strahm and Perez joined the investigation with Detective Hoffman after the discovery of Kerry's corpse, withholding some of the info Kerry had given them from Hoffman. They were then led to believe that the two officers in danger were Lieutenant Rigg and Hoffman, after the two disappeared. Learning of Rigg's tests, the two agents arrived at Rigg's apartment, where they found Brenda's corpse, along with a message on the wall and some pictures that led them to Jill Tuck, John Kramer's ex-wife.
While questioning her on the side about her ex-husband, Perez and Strahm followed after Rigg, realizing that he was either being set-up to look like an accomplice of Jigsaw's, being recruited, or was in fact an apprentice. After arriving at Rigg's FEEL WHAT I FEEL test, they learned that the room that Ivan had been killed in was being rented, for the past six days, by a man named Art Blank, who had been missing for two weeks. Learning of more properties owned by him, they arrived at the most recent residence owned by Art. There, the two agents found two folders, one that repeated the message they had already received, "OPEN THE DOOR AND YOU'LL FIND ME" (intended for Strahm), while the second read, "YOU ARE IN DANGER OF GETTING TOO CLOSE... STEP BACK" (a hint for Perez). After tearing a camera from the wall, Strahm deduced that he and Perez were in fact the two officers in danger.
While waiting for the address of the last of Art's owned buildings (believing it to be Jigsaw's lair or the location of Rigg's last game), Perez and Strahm arrived at the scene of Rigg's SAVE AS I SAVE test. After learning that the building they were in, an abandoned school, was in fact the last owned by Art (who shared ownership with one of his clients, Jill Tuck), Strahm and Perez checked the school office, where a Billy puppet sat in a chair, surrounded by candles, with a tape recorder around the puppet's neck. Perez pressed the play button and heard a message intended for her. It informed her that her partner was going to kill an innocent man (later revealed to be Jeff Denlon) and that her "next move [was] critical," hinting that she should get out of the way. The puppet's eyes began to turn as a faint recording of Jigsaw's voice began playing, and Perez leaned forward to hear what it was saying.
|“||Hello, Agent Perez and welcome to the world you have long studied. Your partner Agent Strahm will soon take the life of an innocent man. Heed my warning, Agent Perez: Your next move is critical.||”|
— Jigsaw warning Perez[src]
Suddenly, the puppet's face then exploded, sending shrapnel into Perez's face and neck, while letting off its mocking laugh, which began to slow down and stop from the damage done to the puppet. Perez's fate was not revealed in the fourth film, although she was rushed to the hospital in critical condition. In the fifth film, Strahm is seen in her hospital room, after she has supposedly died. In the sixth film, it is revealed that Perez is in fact alive and was instructed to fake her own death in the hospital for her own safety, so that she would avoid being targeted by Jigsaw or his apprentice(s).
Returning to question Jill further, Strahm made the realization that Rigg's final test would be at the Gideon Meatpacking Plant after reading an article headline concerning the building, which read "Urban Renewal Group: Four Walls Build A Home". Recalling the message "FOUR WALLS BUILD A HOME" that had been written in paint at the scene of Rigg's first test, Strahm asked Jill where the Gideon plant, which John Kramer had purchased before he became Jigsaw, was located. Rushing to the meat-packing plant, he was close behind Rigg, who was about to participate in his last test. Strahm, however, took a different route, that ended up following Jeff Denlon's tests. Entering Jigsaw's latest warehouse, he opened a large steel door. Inside, he found Jeff in a frantic state after having killed both Jigsaw and Amanda. Waving a gun in the air, Jeff was shot down by Strahm. At that point, the steel door was slammed shut and locked by Hoffman, trapping Strahm inside.