Pregnant Maryland teacher allegedly killed by boyfriend was shot in back of her head: Autopsy Laura Wallen had been missing for over a week when her body was found Wednesday.

 -- A pregnant Maryland teacher who was allegedly killed by her boyfriend was shot in the back of her head, police said, citing autopsy results.

Laura Wallen, 31, of Olney, Maryland, had been missing for over a week when her body was found Wednesday in a shallow grave on property in Damascus, Maryland, the Montgomery County police said.

That day, her boyfriend, Tyler Tessier, 32, was arrested for first-degree murder, police said.

Wallen was four-months pregnant with Tessier's child, Wallen’s sister told detectives.

Wallen, who never made it to the first day of school on Sept. 5, was a social studies and law teacher at Wilde Lake High School in Columbia, where she was awarded “Teacher of the Year” in 2016.

While Wallen was still missing and before the arrest, Tessier spoke at a news conference Monday, holding the hand of Wallen's mother as they appealed to the public for help in locating her.

After Tessier's arrest, however, Montgomery County Police Department Chief Thomas Manger told reporters at a news conference Wednesday night that Tessier was already a person of interest at the time of Monday's news conference after police identified "a couple of inconsistencies in information that he'd given us."

"It was a calculated decision made by detectives to have Tessier attend the event and speak," the Montgomery County police chief told reporters. "It was done with the approval and knowledge of the victim's family."

Wallen's father, Mark Wallen, said at a news conference Thursday, "the press conference we did other day was a press conference to get out a picture and a name of the baby daddy."

"And it was all we could do to be seen as a unified family with him," Mark Wallen said. "He is a monster and he is a liar and it was absolutely the hardest thing that my wife would do, would be to sit next to him and hold his hand. And she had to hold his hands with two hands because she was shaking so badly. But we did it. Because as any father would do, if your child is missing and someone has that child, we were pretty sure it was Tyler, but we didn’t know where she was, and you can’t put someone away on a missing person."

Police said the property where Wallen's body was found belonged to Tessier’s friend.

Between Sept. 5 and 11, detectives interviewed Tessier multiple times, police said, during which, "He admitted that he is engaged to another woman."

Police said Tessier also admitted to throwing away her phone and driver’s license and admitted to driving her car to an apartment complex in Columbia.

"Detectives located an acquaintance of Tessier who stated that Tessier had called her to give him a ride from the apartment complex where [Laura] Wallen’s vehicle was located,” police said. "Tessier asked the friend to lie if the police ever asked her about picking him up in Columbia."

The office of Tessier's defense attorney, assistant public defender Victoria Kawecki, declined to comment on the case Thursday.

Tessier has not yet entered a plea and his preliminary hearing is set for Oct. 13. He's being held without bond.