Authorities announce a second person has been arrested and charged in connection with the shooting deaths of two firefighters in Webster, NY.

Updated: 4:58 p.m. ET: An upstate New York woman was arrested Friday and hit with federal and state charges connected to the fatal shootings of two volunteer firefighters on Christmas Eve.

The woman, Dawn Nguyen, 24, was charged with knowingly making a false statement in the purchase of guns used in the slayings, U.S. Attorney William Hochul told a news conference Friday. She was charged earlier on a state violation of filing a falsified business record.

Hochul said Nguyen bought the guns on behalf of William Spengler, 62, who shot four firefighters responding to a fire he had started in his home on Monday outside Rochester, N.Y., killing two of them, before killing himself.

Nguyen "told the seller of these guns, Gander Mountain in Henrietta, that she was to be the true owner and buyer of the guns instead of William Spengler," he said. "It is absolutely against federal law to provide any materially false information related to the acquisition of firearms."

The complaint alleges that Nguyen acted as a "straw purchaser" for Spengler, who, as a convicted felon, could not legally own, acquire or purchase any firearm, Hochul said. The charges are related to an AR-15-type semiautomatic rifle and a 12-gauge shotgun — two of the three weapons found near Spengler's body Monday, according to State Police Investigator James Sewell.

Hochul said that a suicide note left by Spengler "includes information about obtaining the guns" from Nguyen.

WHEC Police officers escort Dawn Nguyen on Friday.

The third weapon, a .38-caliber revolver, was not connected to Nguyen, Sewell said.

The Rochester Democrat and Chronicle reported that Nguyen was arrested Friday afternoon at the home in Greece where she has been staying with her mother, Dawn Welsher.

Greece is about 5 miles north of Rochester and 2 miles west of Webster, where Spengler lived.

Watch US News crime videos on NBCNews.com

Nguyen's lawyer, Dave Palmiere, told the newspaper that Nguyen bought the weapons legally and that they had been stolen. He said Nguyen didn't recall whether she reported the guns stolen.

Monroe County Sherif's Dept. / EPA William Spengler, in a 2006 photo, who authorities say set a house and car on fire on Christmas eve in Webster, N.Y. and then shot and killed two firefighters, and wounded two others who responded to the blaze.

Welsher told the Democrat and Chronicle that neither she nor her daughter, Nguyen, gave or sold Spengler the weapons.

"This is nuts," she said, according to the newspaper. "I never supplied this man with nothing. My daughter never supplied him with anything. He's setting us up."

The federal charge carries a maximum penalty of ten years in prison and a $250,000 fine, The Associated Press reported.

Spengler spent 17 years in prison for killing his grandmother in 1980.



After Monday's attack, a body was also discovered in Spengler's burned home. Investigators have said they believe the remains are those of his sister, Cheryl Spengler, 67, who lived with him. In all, seven houses were destroyed in the blaze.

Reuters and The Associated Press contributed to this report.

More content from NBCNews.com:

Follow US news from NBCNews.com on Twitter and Facebook