Clint House said he’s still stunned that his former friend, Casey Anthony, was reportedly in good spirits while her daughter was missing.

House has come forward in a new Reelz documentary titled “Casey Anthony: Her Friends Speak,” which features interviews with those who knew “America’s most hated mom," as Nancy Grace once described her.

Anthony’s attorney did not immediately respond to Fox News’ request for comment concerning the airing of Reelz’s show.

Caylee Anthony, 2, was last seen on June 16, 2008, but was first reported missing by her grandmother on July 15. When Anthony was arrested on charges of child neglect, she told police at that time Caylee had disappeared with a babysitter.

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A utility worker working in a wooded area near the Anthony home in Orlando, Fla., found skeletal remains on Dec. 11 that were later determined to be Caylee’s. Experts would testify that air samples indicated that decaying human remains had been present in Anthony’s trunk.

The government, however, failed to establish how Caylee died, and they couldn’t find her mother’s DNA on the duct tape they said was used to suffocate her. After a trial of a month and a half, the jury took less than 11 hours to find Anthony not guilty of first-degree murder, aggravated manslaughter and aggravated child abuse.

Still, Anthony was convicted of four counts of lying to police (though two counts were later dropped) and served about three years in prison while awaiting trial. Today, she lives in the South Florida home of Patrick McKenna, a private detective who was the lead investigator on her defense team. She also works for him, doing online social media searches and other investigative work.

Just four days after Caylee was last seen, Anthony was captured in various photos celebrating at Fusion nightclub and participating in a “hot body contest” at a party hosted by House. However, House insisted that no one in Anthony’s circle knew the toddler had vanished.

Caylee Anthony (AP)

“At that time, none of us knew that Caylee was missing,” he explained. “We couldn’t be surprised. We weren’t surprised until after the fact, until police were talking about it, asking questions. Until the media got ahold of it and things exploded. We were shocked and surprised that she could be out here doing what she had been doing that night, and meanwhile, her child is missing. It came as a big shock once we found out about it. But we just didn’t know.”

House claimed the last time he saw Anthony before the trial was in downtown Orlando on July 3.

“She just didn’t seem like there was anything wrong,” said House. “She was like, ‘Hey, how’s it going? Good to see you.’ Then we went our separate ways. That’s the hardest part about this whole story, is that she was just completely so normal during the time Caylee was supposedly missing.”

House first met Anthony, whom he described at the time as “a fun, bubbly person who liked to have a good time,” in April 2008. She started dating then-boyfriend Anthony Lazzaro, who was living with roommates Cameron Campana, Nathan Lesniewicz and House.

Caylee Anthony with her mother Casey. (Reuters)

“She just pretty much started staying over on a regular basis,” he said. “She never technically moved in… but pretty much she slowly started… staying a little more often.”

House said he met Caylee a few times before she vanished.

“She was a very intelligent 2-year-old,” House recalled. “She was going on 3 [years old] before she went missing, but she was probably one of the sweetest little girls. Very articulate for her age. You could understand 90 percent of the words that were coming out of her mouth when she was talking to you. She seemed just so full of life, and she was just a great little girl. She was very well-behaved.”

In the documentary, House vividly described that Anthony appeared to be a dedicated parent and took her role seriously.

Clint House — Reelz

“What we saw in front of us was a very loving, attentive mother,” said House. “I even testified to that in the trial. That is what I saw with my own two eyes. I never saw her get angry at Caylee. I never saw her grab Caylee in any kind of abusive manner. I never saw her have to discipline Caylee because Caylee was such a well-behaved child… She just seemed like a good mom.”

House first learned Caylee was missing after an ex-girlfriend called and told him to turn on the news. He was stunned to learn that Caylee had disappeared.

“I don’t think you can ever quite prepare yourself for hearing that a little girl you’ve been in contact with within the last couple of months is all of a sudden missing, and she’s been missing for a month,” said House. “There’s nothing you can do to prepare yourself or to hear something like that. It was like a punch in the gut.”

House said he was in disbelief by the reports until he had to sit down and speak with investigators. In the documentary, House visited the spot where Caylee’s remains were found and became emotional by what he witnessed.

Casey Anthony listens to testimony during her murder trial at the Orange County Courthouse on June 30, 2011 in Orlando, Florida. Anthony's defense attorneys argued that she didn't kill her two-year-old daughter Caylee, but that she accidentally drowned. (Getty)

“How was it that all the searchers miss this?” he said. “… It was harrowing to be there and see the leftover remains of all the people that had come and put stuffed animals that had started to decompose into the dirt. That was just really hard, knowing that’s where she ended up. She didn’t deserve that at all. She really didn’t.”

The Florida Department of Children and Families concluded that Anthony was responsible for her daughter’s death because her “actions or the lack of actions… ultimately resulted or contributed to the death of the child.” In 2017, former Circuit Judge Belvin Perry Jr., who presided the trial, theorized that Anthony may have killed Caylee accidentally when she was using chloroform to calm her.

Many people still believe Anthony got away with murder. In response, Anthony told the Associated Press in 2017, “I don’t give a s—- about what anyone thinks about me, I never will. I’m OK with myself, I sleep pretty good at night.”

House said Anthony’s actions from over the years speak for themselves.

In this Feb. 13, 2017 photo, Casey Anthony poses for a portrait next to a photo of her daughter, Caylee, in her West Palm Beach, Fla., bedroom. In an exclusive interview with The Associated Press, Anthony claims the last time she saw Caylee she “believed that she was alive and that she was going to be OK.” (AP Photo/Joshua Replogle) (The Associated Press)

“She’s lying about everything,” he said. “And that interview, where she says she sleeps pretty good at night, are you kidding me? If I was put on trial for killing my kid, and I was acquitted because I didn’t do it, as soon as I walked out those doors at the courthouse, I would be on a manhunt trying to find out who killed my kid. I wouldn’t sleep again until I found out who killed my kid. That says everything you need to know.”

House said he hasn’t heard from Anthony. Several people from over the years have attempted to contact him on Facebook pretending to be her. Today he is a father, which has made him wonder about what really happened to the little girl he once knew.

“The people who will see this will learn that not only was Casey a real person but so are the people who were dragged into this,” he said. “We’re all just regular people that got pulled into a very, very tragic story, and it still affects us to this day. It’s been 10 years since the story broke… [but] it didn’t go away… This really happened to real people, and it still affects us to this day.”

“Casey Anthony: Her Friends Speak” airs Dec. 9 at 8 p.m. on Reelz. The Associated Press contributed to this report.