Casey Anthony’s former cellblock neighbor is telling all.

Robyn Adams, who met "America’s most hated mom" while in an Orange County, Fla. jail in 2008, is appearing on Lifetime’s new series "Cellmate Secrets," which premieres Friday.

The former inmate claimed the two weren’t allowed to speak with each other, but they used "hand signals" to talk from their cell windows. Adams also said the women wrote letters to each other and hid them in books.

According to a clip shared by Yahoo! Entertainment on Wednesday, a book cart that was transported from cell to cell carried those messages. Adams claimed the two chose "one specific" novel to conceal their letters.

However, Adams alleged she didn’t need a secret message to see Anthony's reaction when she learned that the Orange County Sherriff’s Office had located the dead body of her missing 2-year-old daughter Caylee.

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Casey Anthony, who is now 35, was acquitted in 2011 of her daughter’s murder and charges of aggravated child abuse and aggravated manslaughter of a child. But she was found guilty on four counts of providing false information to a law enforcement officer. (Getty Images)

"When they gave her the news that they found Caylee’s remains, it was bad," Adams told cameras.

"They took her to medical, because she couldn’t breathe," Adams alleged. "She was having an anxiety attack, a panic attack."

But prison guard Silvia Hernandez saw the situation differently.

"She didn’t act like a regular mother, where, ‘Oh, they found my daughter and she’s dead?’ – you know, crying, bawling," said Hernandez. "No, no her behavior at that time was like, ‘Oh s—t. I got caught.’"

But Adams insisted she has become one of Anthony’s closest confidantes.

"Apparently, I knew information that no one else knew," she claimed.

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An image displayed on a courtroom monitor shows a photo entered into evidence in the Casey Anthony trial showing the late 2-year-old Caylee Anthony with her mother Casey at the Orange County Courthouse on Friday, June 10, 2011. Celebrity medical examiner Jan Garavaglia testified on Friday that bones scattered in woods near Anthony's home were positively identified as those of her 2-year-old daughter Caylee. REUTERS/Joe Burbank/Pool (UNITED STATES - Tags: CRIME LAW SOCIETY) - GM1E76B0U0J01

Caylee Anthony was supposedly last seen on June 16, 2008; she was first reported missing, by Casey Anthony’s mother, on July 15. A day later, Casey Anthony was arrested on charges of child neglect. She told police that Caylee had disappeared with a babysitter. (Reuters)

Most recently, an anonymous juror who sat at the infamous trial told People magazine that the panel’s decision to acquit Anthony "haunts me to this day."

"I think now if I were to do it over again, I’d push harder to convict her of one of the lesser charges like aggravated manslaughter," the juror explained. "At least that. Or child abuse. I didn’t know what the hell I was doing, and I didn’t stand up for what I believed in at the time."  

"It’s traumatic to think about, and I wish I had done a lot of things differently," the juror continued. "But it’s a part of who I am. This case will stick with me for the rest of my life."

Deadline.com previously reported that "Cellmate Secrets," stems from their hit true-crime special "Jodi Arias: Cellmate Secrets," which aired last year. The show, which focuses on high-profiled cases, will feature interviews with former friends, guards, cellmates and lovers.

Anthony, who is now 35, was acquitted in 2011 of her daughter’s murder and charges of aggravated child abuse and aggravated manslaughter of a child. But she was found guilty on four counts of providing false information to a law enforcement officer.

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Casey Anthony cries next to her attorney Jose Baez (L), after she was acquitted on first degree murder charges of her daughter Caylee at the Orange County Courthouse Orlando, Florida July 5, 2011. REUTERS/Red Huber/Pool (UNITED STATES - Tags: CRIME LAW) - GM1E7760CJW01

Casey Anthony cries next to her attorney Jose Baez (L) after she was acquitted on first-degree murder charges of her daughter Caylee at the Orange County Courthouse Orlando, Florida July 5, 2011. (Reuters)

Defense attorney Jose Baez told jurors that the toddler accidentally drowned in the family pool.

Prosecutors said Anthony used chloroform and then suffocated the child by putting duct tape over her mouth. The toddler’s remains were found five months after she disappeared, in a wooded area not far from where the Anthonys lived. Authorities were never able to establish the cause of death.

The judge who presided over the case, now-former Judge Belvin Perry Jr., told The Associated Press in 2017 that he believed an accidental killing is the most logical explanation for the toddler’s death.  

Perry Jr. said the theory that makes the most sense to him now, based on the evidence presented at trial in 2011, is that Anthony accidentally used too much chloroform while trying to quiet Caylee, and the infant died.

Anthony insisted in a 2017 interview with The AP that she is "still not even certain" what happened to her daughter.  

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According to The Associated Press, Casey Anthony lives in the South Florida home of Patrick McKenna, a private detective who was the lead investigator on her defense team.  (Reuters)

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At the time, the outlet reported Anthony was residing in the South Florida home of Patrick McKenna, a private detective who was the lead investigator on her defense team. She also worked for him, doing online social media searches and other investigative work.

"I don’t give a s--- about what anyone thinks about me, I never will," she said. "I’m OK with myself, I sleep pretty good at night."

Fox News' Stephanie Pagones as The Associated Press contributed to this report.