Laura Wallen, a 31-year-old world history teacher, was four months pregnant when her body was found in a shallow grave in September 2017

By Harriet Sokmensuer
April 06, 2020 12:09 PM
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The murder of a pregnant Maryland teacher in 2017 led to a disturbing revelation about her alleged killer.

Laura Wallen, a 31-year-old world history teacher from Olney, was four months pregnant when her body was found in a shallow grave in Damascus on Sept. 13, 2017, more than a week after she went missing.

How she got there was even more shocking, and is the subject of HLN’s Sex and Murder, new episode, titled “Killer Affair,” airing Monday at 9 p.m. ET/PT.

While Wallen was missing, her boyfriend, Tyler Tessier, then 33, of Damascus, tearfully pleaded for her safe return at a press conference alongside the woman’s parents. But after her body was found, Tessier was arrested and charged with first-degree murder.

Unbeknownst to the public, Tessier also had a fiancée — and authorities allege he killed Wallen to prevent her from telling the fiancée that he had impregnated her, according to charging documents previously obtained by PEOPLE.

“It’s like a TV drama you wish you could shut off,” PEOPLE Staff Writer Steve Helling says in the episode, which features evidence, interrogation material and jail audio released for the first time.

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Laura Wallen
| Credit: Montgomery County Police Department via AP

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Despite the evidence against Tessier, Wallen’s family would never see justice. In 2018, hours before his murder trial was set to begin, Tessier killed himself in his jail cell.

Citing Tessier’s “cowardice,” prosecutor John McCarthy said at a news conference, “We were robbed this morning of the opportunity to allow the public to know the true nature and details of this crime.”

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Tyler Tessier
| Credit: Fox 5 News

Investigators believe Tessier killed Wallen a day after she was seen with him on surveillance video at a grocery store.

The day before, Wallen sent a text message to either her sister or a friend stating “Tyler had taken her to an open field up in the Damascus area.”

Wallen wrote, “I’m not sure why we’re up here, but he’s taken me to this place in the middle of nowhere,” according to police.

The true details of Wallen’s death remain uncertain as Tessier changed his story several times while talking to investigators in the weeks after her body was found.

Prosecutors were seeking a sentence of life in prison without the possibility of parole if Tessier had been convicted.

HLN’s Sex & Murder episode “Killer Affair” premiers Monday at 9pm ET/PT.