A former U.S. Air Force airman already in federal custody as a dangerous child predator has been identified through DNA as a suspect in the torture, rape and slaying of a 9-year-old Missouri girl 25 years ago, authorities said Wednesday.

Earl Webster Cox, 61, is charged with first-degree murder, first-degree kidnapping and sodomy in the Nov. 18, 1993, death of Angie Housman, St. Charles County court records show. According to Federal Bureau of Prisons records, Cox is an inmate at FCI Butner Medium I, a medium-security institution in Butner, North Carolina.

The charges were announced Wednesday during a news conference led by Tim Lohmar, the prosecuting attorney for St. Charles County. Investigators are still looking into the case to determine if anyone else was involved in the slaying.

Detectives “have reason to believe that Earl Cox was not the only suspect,” Lohmar said. He did not elaborate on what the reasoning might be.

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Lohmar said the question of what happened to Angie has haunted residents in the St. Louis area over the past 25 years.

“This case is unique in many ways because it captured the attention of so many of us who grew up here, including myself, and so many of us who were involved in the law enforcement community at the time,” Lohmar said. “So many people who live in this region, who were frightened, terrified that something of this magnitude could happen to a child in our community.”

Angie vanished around 4 p.m. Nov. 18, 1993, after getting off a school bus near her home in St. Ann, a St. Louis suburb, Lohmar said. After she had been gone for a few hours, her mother and stepfather reported her missing.

“The community was in a panic,” Lohmar said. “Law enforcement personnel, dozens upon dozens, if not hundreds, mobilized, along with community volunteers. They scoured the area. They combed the area and talked to every possible witness they could talk to, to no avail.”

Warning: The following description of Angie Housman's death is graphic and might be difficult for some readers. 

A hunter found Angie’s nude body around 10:45 a.m. Nov. 27 in the August A. Busch Memorial Conservation Area just outside St. Louis. She was handcuffed, bound to a tree and partially covered with snow.

The girl’s head was wrapped in duct tape, except for her nose, and she had suffered a “significant, violent sexual assault,” Lohmar said. In her mouth under the duct tape was a torn fragment of her own Barbie-themed underwear, which had been used as a gag.

Near her body, in a Dollar General bag, investigators found two more fragments of her underwear. Angie had deep cuts to her wrists and her thigh, and duct tape appeared to have been put on her wrists to slow down the bleeding, the prosecutor said.

“Crime scene evidence further indicated that Angie was alive as she was bound and left in the woods,” Lohmar said. “She struggled extensively to free herself before she ultimately perished.”

Temperatures the night before Angie was found were below freezing, Lohmar said. Autopsy findings showed the girl died of hypothermia just a few hours before the hunter stumbled upon the crime scene.

That finding indicated she had been kept alive and tortured. Authorities said there were indications she had been starved while being kept captive, though Lohmar said investigators do not know where she was kept before being taken to the woods.

“She was dehydrated, she was malnourished and she was alive when she was left out in the woods to die,” the prosecutor said.

Angie's mother, Diane Bone, died in November 2016 without knowing who killed her daughter, The St. Louis Post-Dispatch reported. The girl is also survived by her stepfather, Ron Bone, and two brothers, including a now-16-year-old brother who never knew his sister, but grew up in the shadow of her slaying.

The family stayed in the duplex where they'd lived with Angie for a few years after her killing, the newspaper reported. Diane Bone kept the curtains closed so she could not see the street from which her daughter had been snatched.

"She'd see the street and the bus stop and bust down crying," Ron Bone told the Post-Dispatch. "She wasn't actually like herself. She wanted to kill herself. I kind of got her out of it (and) her sister got her out of it."

Jackie Bone, Diane Bone’s sister-in-law, said the change in the grieving mother was heartbreaking.

"She never got over it," Jackie Bone said. "There was something missing in her heart."

Watch the entire news conference about Earl Cox's arrest below. 

The Associated Press reported that the disappearance and slaying of Angie, followed by the disappearance of Cassidy Senter, 10, the following month, had authorities scared that a child serial killer was in the community.

A story from the Post-Dispatch's archives indicates that Cassidy, whose body was found Dec. 9, 1993, in an alley in St. Louis, was killed by an ex-convict neighbor who authorities said kept her body in his basement, just 150 yards from her home, until the odor of decay grew too strong.

Thomas Brooks Jr., then 27, confessed to killing the little girl. Sentenced to death in 1994, he died in prison in 2000.

Detectives spent decades searching for Angie’s killer, following hundreds of leads over the years. Investigators lost sleep at night, fretting over the possibility that the case might remain unsolved, Lohmar said.

That changed on Feb. 27, when the St. Charles County crime lab’s senior forensic scientist called a detective with bombshell news: He had found DNA evidence on the pink trim of two of the pieces of Angie’s torn underwear.

The DNA matched two people, Angie and Cox.

“Cox was initially identified through CODIS (the Combined DNA Index System),” Lohmar said. “His DNA was then collected, with his consent, and was retested. Cox was the major contributor of DNA at the location tested.”

Only 1 in 58.1 trillion unrelated people could have contributed the DNA found on Angie’s underwear, the prosecutor said. The Earth’s population is under 8 billion.

“So, multiply the Earth’s population times 8,000, and that’s the likelihood that we find another individual that matches this DNA profile the same as Earl. W. Cox,” Lohmar said.

Cox has a long criminal history involving the sexual abuse of children.

He enlisted in the Air Force in 1975 but was dishonorably discharged a few years later after being accused of the sexual abuse of four children he babysat while stationed in Germany. Lohmar said Cox was court-martialed in 1980 and served several years in prison at Fort Leavenworth.

The parolee was freed in 1985, but he was again on police radar in 1989, when he was questioned about inappropriate contact with two 7-year-old girls in Overland, the Post-Dispatch reported. Cox had reportedly taken the girls to a movie and then to a park behind Buder Elementary School.

Buder Elementary was the school Angie attended at the time of her slaying, the newspaper said.

Cox was again arrested and charged with the sexual abuse of a child in 1992, KSDK in St. Louis reported. He served more time in Fort Leavenworth before being released later that year.

Cox moved back to his native St. Louis, where he lived just three blocks from Angie's home at the time of her disappearance, the news station reported.

The Post-Dispatch reported that Cox's name was on a list of sex offenders that investigators put together four years after Angie was abducted and killed. Lohmar said Wednesday that Cox was never questioned in connection with the case.

Communication among various law enforcement agencies suffered in the days before the internet and online criminal databases, the prosecutor said.

Court documents obtained by KSDK show Cox got involved in a child pornography network in 1997. He was nabbed in an FBI sting while living in Colorado and pleaded guilty in 2003 to trying to entice a minor across state lines and to possessing more than 45,000 images of child porn on his home computer.

Cox has been in federal prison since that conviction.

The court in 2012 certified Cox as a "sexually dangerous person" under the Adam Walsh Child Protection Act, the news station reported. A judge ruled that he should be held in federal custody indefinitely based on the psychiatric evaluations of three experts who found he would be highly likely to reoffend if he was ever released.

"The three experts in this case are unanimous in their opinions that (Cox) will have serious difficulty in refraining from engaging in sexually violent conduct if released," according to the court documents. The suspect "has expressed no empathy for his victims and has failed to acknowledge any wrongdoing on his part. The frequency, severity, and variety of his offenses are extremely troubling," the documents said.

Lohmar, who was a college student when Angie was abducted and slain, said he convened a task force to look at cold cases in 2012, after being appointed county prosecutor. Angie’s case was at the top of the list of cases investigators wanted to reexamine.

“That’s been the case that’s haunted these guys for years,” Lohmar said.

Lohmar said a lot of work went into solving Angie’s homicide over the years.

“This is why we’re happy to be here. This is why we’re proud to be here,” the prosecutor said. “It’s a sad occasion. We are remembering something that was a terrible, terrible tragedy to a young lady who didn’t deserve this, but at the same time today culminates so much effort, so much work, so much passion and dedication.

“It’s something that I think we as a community can be proud of.”

He said that, in Angie’s case, the length of time it took to solve the crime was a “blessing in disguise” because the DNA technology used to identify Cox was not available earlier in the investigation.

“Had we tested this evidence any sooner than we did, there’s a chance that nothing would have come about because the technology just wasn't advanced enough,” Lohmar said. “Time was actually on our side on this one, because had this piece been tested before the current technology was available, it would have been discarded and we may never have found the profile.”

Ron Bone told the Post-Dispatch his family moved in 1999 from the home where Angie lived with them. His wife would still leave a light on for her daughter, even all those years after she had been killed.

The family took with them Angie’s clothes and stuffed animals, as well as her beloved bicycle, which she had won from a toy store when she was 7 years old.

Bone still has Angie’s bike in the shed in his backyard.

He said he is glad to have some answers about his stepdaughter's death, even 25 years later. Bone told KSDK that investigators showed him a photo of Cox several weeks ago after the DNA results pointed to him.

"They said they matched (the DNA) out to somebody I was supposed to know," Bone told the news station. "I don't know who it is. They showed me a picture of the person. He looks familiar, but you're talking 25, 27 years ago."

Bone told the AP he was glad charges had been filed but was leery of getting too excited.

"I can't say anything about being happy until he's found guilty," Bone said.