A “person of interest” in a Delaware County double-homicide is linked the the Jan. 20 shooting death of a federal agent in Vermont near the Canadian border.

A shootout occurred when the Customs and Border Control agent, David “Chris” Maland, 44, stopped a car with suspects Teresa Youngblut, 21, of Seattle and a German national, Felix Baukholt.

Baukholt, who was in the U.S. on an expired visa, was killed during the encounter. Youngblut was injured.

Youngblut is charged with one count of using a deadly weapon while assaulting Maland and discharging a firearm during and in relation to that assault, authorities said.

According to the Department of Justice (DOJ), Youngblut and Baukholt had been on authorities’ radar after a motel clerk in Lyndonville, Vt. reached out to federal agents the previous Tuesday when the couple checked in, reportedly armed and wearing black tactical gear. Investigators also spotted Baukholt and Youngblut walking in public in downtown Newport wearing the same gear and openly carrying firearms.

Vermont is an open-carry state. Federal investigators reported trying to interact with the couple but said they were not interested in talking and indicated they were in the region shopping for real estate.

It’s still unclear from the DOJ affidavit who was directly responsible for the shooting death of Maland.

“During the stop, Youngblut fired her handgun without warning toward at least one of the Border Patrol Agents while outside the vehicle,” the affidavit states. “Her German companion also tried to draw a firearm, and at least one Border Patrol Agent fired his service weapon. The exchange of gunfire resulted in Border Patrol Agent David Maland sustaining fatal injuries. Youngblut and her companion were also shot. The German man was pronounced dead at the scene, and Youngblut was taken to the hospital for medical care.”

The affidavit noted agents found the following items inside Youngblut’s Toyota: A ballistic helmet; night-vision goggles, one tactical belt complete with a holster; one magazine loaded with cartridges, two full-face breathing respirators, 48 rounds of .380-caliber, hollow-point bullets, one package of shooting range targets — including some already used — two handheld two-way radios, roughly a dozen electronic devices  and multiple electronic storage devices, documents containing identification, utility, lease, travel, and lodging information related to several states, and “an apparent journal” found with Youngblut’s identification papers.

According to court filings that were presented to a judge Monday by Assistant U.S. Attorney Matthew Lasher, a reason to detain Youngblut was her “associations with other individuals suspected of violent acts.”

Lasher wrote the person who bought the firearms Youngblut and Buackholt had at the time of the Vermont shooting was “a person of interest” in a double-homicide in Delaware County. And Buckholt flew to the U.S. just hours before that homicide. The person detained in the Delaware County homicides is also a person of interest in a homicide investigation in Vallejo, Calif., Lasher said.

Lasher did not name the person of interest in his filing.

The Delaware County District Attorney’s Office, the Philadelphia FBI Office, and the Pennsylvania State Police did not respond to DV Journal’s attempts to ascertain the name of the person of interest referred to in the Youngblut case.

Also, acting U.S. Attorney Michael P. Drescher has asked the court to seal the Youngblut case files.

He asserted Youngblut “poses a current and substantial danger to the community.”

Investigative journalist Andy Ngo reports both Youngblut and Baukholt were militant “trans activists.”