The Walking Dead revealed the secret culprit behind Negan's (Jeffrey Dean Morgan) jailbreak in Sunday's Season 10 episode 12, "Walk With Us." After spending some eight years locked up as the lone prisoner in the Alexandria jail, Negan was set loose while awaiting a vote on his fate in Season 10 episode 4, "Silence the Whisperers," where an uncaged Negan accidentally killed Margo (Jerri Tubbs) when rescuing defector Whisperer Lydia (Cassady McClincy) from a violent ambush. The fugitive Negan, gifted his leather jacket and a replica Lucille baseball bat by Savior fanboy Brandon (Blaine Kern III), then crossed into Whisperer territory and seemingly pledged his loyalty to Alpha (Samantha Morton).
After participating in the fiery attack on Hilltop that left the colony once led by Maggie Rhee (Lauren Cohan) in ruins, the masked Negan is sent out by Beta (Ryan Hurst) to herd walkers to join Alpha's undead army. "I do not have everything I want," Alpha says, referring to daughter Lydia, who refused to kill her mother and take her place as pack leader.
The dead "will not stop until I bring her home to you," growls loyal follower Beta (Ryan Hurst), promising to send the walker army after the survivors harboring Lydia. But she's first spotted and snatched by Negan, who tells Alpha he's "found that thing" she's been looking for.
Bringing Alpha to a shack in the woods, Negan marches Alpha towards her daughter. "Lydia was made for this. To be free," she says. "With me." When Negan notes she still loves her daughter, Alpha tells him, "I have to do it because I love her. She will always be my baby."
Closing in for the kill, Alpha is bewildered to find an empty shack. Lydia is somewhere else, far from her mother, who realizes too late she's been lured into a trap. Negan slices Alpha's throat, cradling her as she bleeds out and dies.
Carrying a bloodied sack through the woods, Negan slings its contents like a bowling ball. Alpha's reanimated and decapitated head rolls, stopping at the feet of Carol (Melissa McBride), who tells him: "Took you long enough."
"I think that, moving forward, our group is in big trouble with the Whisperers, much more trouble than they were in with Negan and the Saviors. And if I think if someone can step forward and help, it’s Negan," Morgan said on a past episode of Talking Dead ahead of Season 10. "Will our group be open to that? I mean, honestly, I don't know what's in Angela [Kang, showrunner] or [TWD chief content officer Scott Gimple's] mind and what they have in store."
"But I would love to see him get a chance to work with our group," Morgan added. "Just give him the chance."