Dateline: Secrets Uncovered: What happened to Heidi Allen?

Heidi Allen, an eighteen-year-old college student who worked part-time at a convenience store in New Haven, New York, went missing in the middle of her shift in April 1994, and authorities believe her case remains unsolved, despite the conviction of one man. Another factor that remains unknown is Allen's whereabouts and what exactly happened to her nearly three decades ago.

Despite the fact that the case has taken several twists and turns over the years, the Oswego County Sheriff's Department and the Federal Bureau of Investigation are still "considering the matter to be an open case," according to an October 2022 report. Authorities are constantly working on the case, and actively following leads in an effort to find the remains of the missing woman.

On Wednesday, November 16, 2022, at 7:00 p.m. ET, Dateline: Secrets Uncovered on Oxygen will re-air an old episode called "The Informant" in an attempt to look at the case of Heidi Allen again.

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Heidi Allen mysteriously disappeared from her workplace in the middle of her shift

Heidi Allen, an 18-year-old college student who worked part-time at a gas station in New Haven, New York, went missing on Easter morning, April 1994, around 8 a.m., in the middle of her shift. Despite the fact that it has been decades since that fateful day, the missing case remains a mystery.

According to sources, she opened the store around 5:45 a.m. and was covering the shift for another employee. Her boyfriend was with her at the time and left as soon as people began to arrive and the place became busier. In the episode, Allen's sister Lisa Buske explained the sequence of events, saying:

"He would take her so that she wasn’t alone until people, you know, like the traffic was picking up, and then he would go."

The last person to enter the store that morning before Allen mysteriously vanished was a man named Richard Thibodeau, whose brother Gary Thibodeau was later convicted in the case. He even recalled getting two boxes of cigarettes. Gary died in prison while maintaining his innocence.

However, by the time the others arrived, Allen had left, but her car remained parked. Worried customers quickly called a deputy, and the investigation into the case of the missing 18-year-old, whose body has yet to be found, began.

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Gary Thibodeau was convicted in connection to Heidi Allen's disappearance

Richard Thibodeau contacted authorities after learning of Heidi Allen's disappearance. Simultaneously, many people reported seeing a strange van at the convenience store around the time of the incident. During the course of the investigation, Richard allegedly drove a white van that matched the description of the vehicle seen by one of the witnesses at the scene.

Furthermore, surveillance footage revealed that Richard and his brother Gary were the two men at the gas station that morning. Gary Thibodeau, who had an alibi that morning, was arrested on drug-related charges subsequently that day. Two other prisoners later informed investigators that Gary had confessed to killing Allen as part of a botched drug deal while he was in custody.

The evidence discovered was sufficient for detectives to arrest Gary and Richard for first-degree kidnapping. Richard, on the other hand, was acquitted, whereas Gary was found guilty by a jury in 1995 after a trial.

Years later, it was revealed that Heidi Allen was working as a teen drug informant under the alias "Julia Roberts" at the time of her disappearance and that the deputy she was working with had lost an identification card two years prior to the incident, in which it was stated that Allen was an informant.

Gary's defense team didn't have this important piece of information, which may or may not have changed the case. Even though Gary's lawyers took his case all the way to the state's highest court, he never got a new trial and ended up dying in jail.

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Learn more about Heidi Allen's case on Dateline: Secrets Uncovered, this Wednesday, November 16, 2022.