13 Reasons Why” star Ross Butler recently opened up about the major cliffhanger involving Alex (Miles Heizer) and his own character, Zach.

In the 13th episode of the hit Netflix series, Zach sent Alex several text messages, but he only received one reply from him. The latter asked Zach to call him, but when he did, it wasn’t Alex who picked up the phone.

While speaking with Entertainment Weekly, Butler revealed who he thinks answered Alex’s phone. “I imagine it was his dad. Or maybe some police investigator on the scene, because Zach had been sending texts. I didn’t think too much. He sent out a call and the scene cuts,” he said.

Read: “13 Reasons Why” star Dylan Minnette opens up about his favorite scenes

Even though it is unclear who Zach talked to on the phone, Butler reiterated the fact that his character developed a close friendship with Alex throughout the show. “Out of all of them, Zach had been really worried about Alex because he’d seen that Alex had been having issues with his stomach and that he’d been getting really depressed. In the texts, you see that there’s a lot of outgoing texts to Alex, but no responses,” he explained.

Meanwhile, there are some speculations suggesting that Alex did not shoot himself. Rather, it was Tyler (Devin Druid) who killed him. In one of the scenes, Tyler went to the red room and pulled out Alex’s photo. He was also seen with a gun, and he’s very much upset with Alex for bullying him for years. Unfortunately, book author Jay Asher has not commented on the fan theory. But he has hinted on the possibility of releasing a sequel for television and not the book.

13 Reasons Why” started streaming on Netflix on March 31.