On Monday, federal prosecutors announced murder and stalking charges against a man suspected of shooting two Minnesota state lawmakers and their spouses. The accused reportedly also visited the homes of two other officials and left behind a notebook with dozens of names.

Vance Boelter, 57, was apprehended on state murder charges Sunday night following a two-day manhunt. Although Minnesota does not have the death penalty, federal prosecutors might seek capital punishment if Boelter is convicted on the six new federal charges.

Authorities allege that Boelter shot and killed former Minnesota Democratic House Speaker Melissa Hortman and her husband, Mark Hortman, at their residence early Saturday. Additionally, he is accused of injuring state Sen. John Hoffman (D) and his wife, Yvette, during a shooting at their home, located about 8 miles away, the same morning.

According to a newly unsealed affidavit, Boelter also visited the homes of two other elected officials that morning. Neither official was identified, but Boelter allegedly left one house after finding that no one was home, and police saw him in a dark SUV at the other before he drove off.

Boelter faces a stalking charge for each lawmaker he shot, murder charges for the killings of Hortman and her husband and two counts of using a firearm during a crime of violence. 

Joe Thompson, the acting U.S. attorney for Minnesota, at a Monday press conference announcing the charges said Boelter “stalked his victims like prey.” 

“It is no exaggeration to say this is the stuff of nightmares,” Thompson said. 

He declined to say whether he would seek the death penalty but did not rule it out. 

“It’s too early to tell, but that is one of the options for several of the charges,” he said. 

The new affidavit provides the most detailed account yet of Boelter’s alleged actions.

When fleeing the Hortmans’ home, the final one he visited, he allegedly left behind his SUV, where police found five firearms and a “large quantity” of ammunition. They also discovered several notebooks filled with the names of more than 45 Minnesota state and federal public officials and lists of internet-based search engines to query people’s addresses, the documents show.

“This was a targeted attack against individuals who answered the call to public service,” Alvin Winston, special agent in charge at the FBI’s Minneapolis field office, said at Monday’s press conference.

In the surrounding area, the affidavit says police discovered the facemask Boelter purportedly wore and a Beretta 92 9mm semiautomatic handgun he purchased in 2000.

The documents indicate Boetler texted his family group chat just after 6 a.m. that morning, writing, “Dad went to war last night…. I don’t wanna say more because I don’t wanna implicate anybody.”

“Words are not gonna explain how sorry I am for this situation…. there’s gonna be some people coming to the house armed and trigger-happy and I don’t want you guys around,” Boelter texted his wife in a separate message, according to the affidavit. She gave authorities consent to search her phone.

Police arrested Boelter Sunday night after discovering his Buick, which he allegedly purchased on Saturday from an unnamed witness, abandoned on the side of a highway.

In the Buick, authorities say they found a letter, authored by someone claiming to be Boelter, that admits to being “the shooter at large in Minnesota involved in the 2 shootings the morning of Saturday June 15th.”

—Miriam Waldvogel contributed to this report, which was last updated at 1:33 p.m. EDT