Montgomery County Police arrested a man on Wednesday in connection to the murder of his pregnant girlfriend, who had been reported missing last week. Police eventually discovered Laura Wallen’s body in a freshly dug grave in Damascus, Md. An autopsy found that she was shot in the back of her head.

Two days before his arrest, Tyler Tessier pleaded for his girlfriend’s safe return at a news conference.

“If somebody has her, please understand that you’ve taken away a huge person in so many people’s lives,” Tessier said. “I know what she means to me. I know what she means to everyone else. We just want to know that she’s ok, we just want her back.”

Montgomery County Police chief Thomas Manger said at a press conference that officials made a “calculated decision” to have Tessier speak at the press conference because of inconsistencies in information that he’d provided.

Police arrested Tessier nine days after Wallen’s family became worried that she didn’t show up to teach on the first day of school at Wilde Lake High School in Columbia, Md.

Manger said that Wallen was last seen with Tessier, which was caught by surveillance footage at a grocery store in Columbia, on September 2. That same day, Manger said she texted a friend saying Tesslier had taken her to an open field, and she didn’t know why. She sent a photo of the area, which police say appears to be the same place her body was later found.

Detectives suspect she was killed on September 3.

On September 4, Manger said Wallen’s sister received a text message from her phone, but this time the messages came from Tessier.

The messages talked about Tessier being a great guy, according to The Washington Post. Although police believe Tessier was the father of the child Wallen was carrying, the text message claimed that he was not.

Police found Wallen’s car parked in an apartment complex in Columbia on September 7. Tessier later admitted to moving the front tag off the car, as well as throwing away Wallen’s driver’s license and phone. He also allegedly texted a friend saying he needed help “cleaning up a mess.”

Authorities determined that Tessier had recently made several visits to a private property in Damascus, where police found Wallen’s body in a shallow grave around noon on September 13. He was arrested later that afternoon and charged with murder.

Manger said there are speculations that Tessier killed his girlfriend because he was in another relationship and because Wallen was pregnant, but he can’t confirm a motive.

This post has been updated with the cause of Wallen’s death.