911 operator Kim Archuletta says her 1996 call with Patsy Ramsey "disturbed" her
Credit: CBS

The woman on the other end of Patsy Ramsey‘s frantic December 1996 911 call – made after finding a ransom note for her 6-year-old daughter JonBenét – spoke out for the first time in the premiere episode of CBS’ The Case of: JonBenét Ramsey, Sunday.

Kim Archuletta, the Boulder, Colorado, 911 operator who took Patsy’s call, detailed the dramatic phone conversation to investigators Laura Richards, a former Scotland Yard behavioral analyst, and Jim Clemente, a retired FBI profiler, who are digging into the case with a team of experts ahead of the 20th anniversary.

“This is the first time that anyone’s asked for my opinion in 20 years,” Archuletta said. “I just remember having that sunken feeling, like something wasn’t right. The problem was, if you hear the frantic in her voice when she’s speaking to me, where she couldn’t even answer my questions, it immediately stopped.”

Patsy phoned police just after 5 a.m. on December 26, frantically revealing that she discovered a two-and-a-half page note asking for $118,000 for JonBenét’s safe return. Following the short conversation, Ramsey appeared to try to hang up the phone – but many have said voices can still be heard on the line.

WATCH: 5 Clues That Could Reveal What Really Happened To JonBenét Ramsey

“What bothered me immensely, it sounded like she said ‘Okay, we’ve called the police, now what?’ ” explained Archuletta. “And that disturbed me. So I remained on the phone, trying to hear what was being said. It sounded like there were two voices in the room, maybe three different ones. I had a bad feeling about this. To me, it seemed rehearsed… that’s never changed.”

Later that day, JonBenét’s body was found in the family’s basement with a garrote around her neck and duct tape over her mouth.

Archuletta said that an investigator came to her home shortly after the murder and told her that she was under a gag order until charges were made. She was also not contacted to testify during the 1999 grand jury indictment of Patsy and husband John Ramsey, after which former District Attorney Alex Hunter declined to prosecute the couple.

“There were things being said that somebody needed to know,” Archuletta told Clemente and Richards. “It was never addressed. I think it would have really turned the case around.”

Neither Patsy nor John, as well as son Burke – who was 9 at the time – were ever charged in JonBenét’s murder. John and Burke are the family’s only surviving members: Patsy died in 2006 after a battle with ovarian cancer – two years before District Attorney Mary Lacy wrote a letter to John saying that DNA evidence cleared the trio.

The investigators further analyzed the call with an audio engineer, using noise reduction to try to determine what was said after Patsy thought she’d hung up.

After working on the formerly inaudible segments, Clemente and Richards decided they thought they heard an adult male say, “We’re not speaking to you”; an adult female ask “What did you do?”; and a “smaller voice” ask “what did you find?”

Also in the episode, Richards and Clemente were joined by Dr. Henry Lee, a forensic scientist; Jim Fitzgerald, a forensic linguist; James Kolar, an investigator for the Boulder District Attorney; Stan Burke, a former FBI special agent; and Dr. Werner Spitz, a forensic pathologist, in their self-described “war room.”

The group also analyzed the ransom note, looking at wording, writing and more, before ultimately deciding that it was a “red herring” crafted by a female, age 30 or over.

Further, they recreate the Ramsey home and later speak with the family’s friends.

During a conversation with Judith Miller, who was in the Ramsey’s close circle and played on a softball team with the couple, she revealed that she was advised not to speak to police or reporters. Miller, who said she “loved [JonBenét] very much,” told Clemente and Richards she felt, however, that speaking out would help.

“I opened my doors up to reporters, and then talked to police twice,” she explained. “They just cut me off as a friend.”

Part two of The Case of: JonBenét Ramsey airs Sept. 19 at 9:00 p.m. on CBS.