Catherine Serou, 34, had not been heard from since Tuesday night after she got into an unidentified car outside her residence in a suburb of Nizhny Novgorod, around 250 miles east of Moscow.

Before her discovery, her mother, Beccy Serou, told NPR from Vicksburg, Mississippi that she had received a message from her daughter that read, “in a car with a stranger. I hope I’m not being abducted.”

She said that her daughter was in a hurry to get to a clinic and so may have got into a passing car rather than wait for an Uber.

“I think that when she saw that the person wasn’t driving to the clinic, but instead was driving into a forest, she panicked,” Beccy Serou said, “her telephone last pinged off a cell tower in that forest.”

A criminal investigation into her disappearance was launched and a large-scale search operation was undertaken.

A public appeal was made on social media and more than 100 volunteers combed the forests north of the suburb of Bor.

The regional federal investigative committee said in a statement on Saturday that after the search “the girl’s body was discovered,” without naming the victim.

It said a man born in 1977 who had previous convictions for “serious” crimes had been arrested on suspicion of murder.

Catherine Serou had enrolled in a master’s program in law at Lobachevsky University in the city in 2019 and wanted to learn Russian before becoming an immigration lawyer.

She had graduated from the University of California with a master’s degree in art history and had served in the Marine Corps, doing one tour in Afghanistan.

Beccy Serou said that she had hoped her daughter’s survival skills learned as a marine would have held her in good stead.

On Saturday, NPR journalist Lucian Kim, who had interviewed Beccy Serou, tweeted a video of her daughter previously giving an interview in Russian and English to a local news channel.

He tweeted that her disappearance had “moved me the most since I started covering Russia for NPR 5 years ago,” describing her story as one of a “young American coming to Russia with high hopes and her mother Beccy’s fortitude as darkness closed in, thousands of miles away.”

Newsweek has contacted Russia’s investigative committee for comment.