The woman allegedly connected to the death of a U.S. border patrol agent in northern Vermont used a gun bought by someone who was a person of interest in a double murder in Pennsylvania and California, federal prosecutors revealed Monday.

Teresa Youngblut, 21, faces two weapons charges in connection with the death of Border Patrol Agent David Maland, 44, who died Jan. 20 during a deadly traffic stop shootout in Coventry, Vermont. She had been traveling with Felix Bauckholt, a German citizen who was killed.

According to prosecutors, the gun used by Youngblut and the one that Bauckholt was carrying are linked to a third person in Vermont. The buyer, prosecutors said, is a person of interest in a double homicide investigation in Pennsylvania, U.S. Attorney Michael Drescher said.

That individual is also a person of interest in a murder investigation in Vallejo, California, federal prosecutors said. No other details were provided.

“An originally peaceful interaction between the United States Border Patrol and the occupants of a vehicle became confrontational based on the defendant’s conduct, and she then unnecessarily and inexplicably escalated to deadly violence,” prosecutors said in a Monday court filing.

Maland, a Minnesota native and U.S. Air Force veteran, worked as a Border Patrol agent at the U.S. Customs and Border Protection’s Newport Station.

This undated image courtesy of Joan Maland shows U.S. Border Patrol agent David Maland, who was killed Monday, Jan. 20, 2025, following a traffic stop in Vermont.  (David Maland/Joan Maland via AP)

Youngblut made her first court appearance on Monday in Burlington, Vermont.

“This investigation remains very active, and the legal process continues,” FBI spokesperson Sarah Ruane said.

Fox News Digital has reached out to the U.S. District Court in Burlington and the U. S. Attorney’s Office for the District of Vermont for comment.

Fox News’ Audrey Conklin and the Associated Press contributed to this report.