Now that one of the founders of the BAU has been killed off the show, fans have been left wondering what will happen next on "Criminal Minds."

Last Wednesday, viewers said goodbye to Jason Gideon after he was tragically murdered by the Unsub that he was trying to track down. The body of the former BAU leader was discovered inside of his own cabin within the first few moments of the episode, notes Hollywood Life.

While David Rossi was trying to find the suspect who murdered his longtime friend and colleague, the show flashed back to 1978, when Rossi and Gideon were first trying to crack a case that was left unsolved. Back then, it was just the two partners running the BAU. Ben Savage guest starred on the show, playing a young Gideon, while a young Rossi was played by Robert Dunne.

Eventually, Rossi solves the 1978 case and captures Gideon's killer. He then killed him in order to avenge Gideon's death.

In an interview with TV Guide, executive producer Erica Messer explained why Gideon was killed off the show, and how Reid will deal with the loss of his mentor and friend.

According to Messer, she came up with the idea to permanently eliminate Gideon a while ago.

"I had the idea of the '70s of it all more than anything. And then it was like, 'What is an important enough case that would warrant us going back and seeing where it all started?' Having it be this character, who we haven't seen in forever but we're going to see where it started with him, it just felt right to see where it all ends for him," said the showrunner.

"You're seeing his whole life as an FBI agent and the personal side of having a child he wanted to have but maybe wasn't as good of a dad as he wanted to be. It felt like a really nice way of honoring Gideon. We don't kill off our heroes very often. We did Strauss obviously. But it felt like after 10 years, these are things that do happen to agents who have worked together for a long time. Their friends die, even in the line of duty. All of our fans who've been watching for 10 years, all of us who've been working here 10 years and the actors who've been living these characters for 10 years -- it was like, 'Let's give them some real drama.' When it hits home, it doesn't get more real than that," she added.

Unfortunately, Reid is going to take Gideon's death the hardest.

"Reid's now seen a lot of loss the past few years. He's sort of matured in that way that we all do. Death can happen to us at any time. There will be a sadness there that plays into the next episode a little bit, but it's his version of dealing with it. It's really bittersweet. Rick Dunkle wrote that one. It sort of continues the tribute to the character, especially the history between Rossi and Gideon, and Reid and Gideon, so therefore Rossi and Reid. It's a really lovely continuation and then it becomes one of those things that the characters add to their layers. They've seen deaths of colleagues. It makes you look at the job differently. I love how Hotch and Rossi had such a nice moment at the end. They didn't say anything about murder for once."

Messer also teased how Gideon's death will affect the other characters.

"It's a really lovely continuation and then it becomes one of those things that the characters add to their layers," she said. "They've seen deaths of colleagues. It makes you look at the job differently. I love how Hotch (Thomas Gibson) and Rossi (Joe Mantegna) had such a nice moment at the end. They didn't say anything about murder for once."

On a bright side, Messer hinted that fans may seen more of Ben Savage starring on the show.

"He was so good -- I think it's certainly something that excites all of us," she said. "You won't see him again in Season 10, but it's something we're considering for the future."

In the next episode, which is entitled "Hero Worship," the BAU will go on the hunt for a suspect who uses homemade bombs to blow up public areas.

According to Carter Matt, the synopsis reads as follows:

"When an Indianapolis coffee shop is blown up and a hero emerges from the wreckage, the BAU tries to protect that person and his family while searching for the UnSub before more incidents occur."

Season 10, Episode 14 of "Criminal Minds," "Hero Worship," will air on Wednesday, Feb. 4, on CBS.