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GAITHERSBURG, Md. - Autopsy results have revealed that a pregnant Maryland teacher who was found dead in Montgomery County was shot in the back of the head, police said.
The body of Laura Wallen was discovered in a shallow grave in a field in Damascus on Wednesday after she was reported missing for over a week by her family. After the discovery, Tyler Tessier, the father of Wallen's unborn baby, was charged with her murder.
The 31-year-old Olney woman was a beloved social studies teacher at Wilde Lake High School in Howard County. She was four months pregnant when she died.
On Thursday, authorities revealed that the motive for the murder is believed to be connected to a love triangle between Tessier, Wallen and another woman Tessier was engaged to. Officials said Wallen had recently reached out to the other woman to set up a face-to-face meeting and investigators believe she was possibly going to tell her that she was pregnant with Tessier's child.
RELATED: Letting Tyler Tessier speak at Laura Wallen's news conference part of police strategy
Wallen was first reported missing on Sept. 4 by her sister. Police determined that the last known financial transaction from Laura Wallen's account was a debit card purchase at the Safeway store in Olney on Sept. 2 between 8:30 p.m. and 9:30 p.m. The store's surveillance cameras showed Laura Wallen and Tessier making a purchase together.
Police say the last message from Laura Wallen's phone was to her sister on the morning Sept. 4. It was a text message detectives said Tessier admitted to sending himself.
Officers said an employee of the Gramercy Place apartment complex in Columbia located Laura Wallen's license in front of an apartment dumpster on Sept. 4. When police responded they also found Laura Wallen's vehicle, a 2011 black Ford Escape.
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Between Sept. 5 and 11, detectives said they interviewed Tessier multiple times. They said in each interview, Tessier provided conflicting statements regarding Laura Wallen's disappearance. They also said he made some admissions including the fact that he was engaged to another woman. Police said Tessier also admitted that he drove Laura Wallen's vehicle to the apartment complex in Columbia, Maryland and disposed of her phone and driver's license in a dumpster, and then removed her license plate from her vehicle.
Police said they located an acquaintance of Tessier who told them that Tessier had called her and asked her to give him a ride from the apartment complex where Laura Wallen's vehicle was located. Investigators also said Tessier asked the friend to lie if police ever asked her about picking him up. Detectives also said Tessier contacted an acquaintance last Sunday night asking for a ride to Baltimore for help "to clean up a mess." The acquaintance refused to assist him.
On Sept. 13, police said they executed a search warrant on property along Prices Distillery Road in Damascus, Maryland. The property, belonging to Tessier's friend, included a farm surrounded by acres of open fields and woods.
Authorities said Tessier had been spending a lot of time at the property after Laura Wallen's reported disappearance. During the search, police said they located a freshly dug area of the ground in a field adjacent to the friend's property. It was there they said they discovered Laura Wallen's body.
FOX 5's coverage on the disappearance of Laura Wallen:
Laura Wallen's murder linked to love triangle, police believe
Letting Tyler Tessier speak at Laura Wallen's news conference part of police strategy
Body of missing pregnant Maryland teacher found; boyfriend arrested
Missing pregnant teacher's family offers $25,000 reward
Vehicle of missing pregnant Maryland teacher found in Howard County
Students coming together to help in search for missing pregnant Md. high school teacher
Wilde Lake High School students hoping for safe return of missing teacher Laura Wallen
Search continues for missing pregnant Maryland teacher
Police searching for missing pregnant Maryland teacher