Catching Minnesota assassination suspect: How a hunch and a mistake led to his arrest

Accused Minnesota assassin Vance Boelter's alleged plan to kill more politicians on his target list was foiled by a police sergeant's proactive hunch, and his capture came after he made a big misstep that exposed his whereabouts to an eagle-eyed neighbor, authorities said.

Boelter was captured Sunday night following what officials described as the largest manhunt in Minnesota history. His arrest came roughly 43 hours after he allegedly assassinated Rep. Melissa Hortman, D-Minn., and her husband, Mark, in their home and shot Sen. John Hoffman, D-Minn., and his wife, Yvette, in their residence while disguised as a police officer.

At the onset of the manhunt, police discovered a notebook in the alleged gunman's abandoned, fake police vehicle containing a list of elected officials who investigators suspect were targeted in a plot that the Minnesota U.S. attorney described as the "stuff of nightmares."

Sergeant's hunch foils suspect's alleged plan

Police were first alerted to the shooting at Sen. Hoffman's home in the Minneapolis suburb of Champlin when Hoffman's young daughter called 911 at 2:05 a.m. on Saturday and reported her parents had been shot by an intruder, officials said.

After hearing of the shooting at Sen. Hoffman's home, a police sergeant in the nearby town of Brooklyn Park had a hunch and acted on it, Brooklyn Park Police Chief Mark Bruley said at a news conference on Monday.

Brooklyn Park Police officials confirmed to ABC News on Tuesday that the sergeant's name is Rielly Nordan.

Burley said the Sgt. Nordan had just finished his shift and was walking out of the police station when he heard of the shooting at Hoffman's house.

"Being alert, seeing two officers in the police department, he said, 'Hey, drive by Melissa Hortman's house and just check on the house, would you?'" Burley said.

The two Brooklyn Park police officers arrived at Rep. Hortman's home to conduct a welfare check around 3:30 a.m. just as the suspect, dressed as a police officer and wearing a hyper-realistic mask, was walking up to the front door, authorities said. The suspect's black SUV -- which was made to look like a police vehicle fitted with flashing emergency lights and a license plate reading "Police" -- was parked in the driveway, the official said.

When the Brooklyn Park officers got out of their car, the suspect, Boelter, allegedly drew a handgun and opened fire, according to Minnesota U.S. Attorney Joseph Thompson. But Drew Evans, superintendent of the Minnesota Bureau of Criminal Apprehension, said it remains under investigation whether Boelter fired at the officers or was shooting into the door of Hortman's home.

When officers opened fire, the suspect entered the home, fatally shooting Hortman and her husband, Mark.

Boelter allegedly ran out the back door. Police found the suspect's 9mm Beretta, body armor and mask ditched behind Hortman's home.

In Boelter's vehicle, still parked in the driveway, officers discover five more firearms, including assault-style rifles and a large quantity of ammunition, Thompson said. Also in the car, they found a notebook containing the names and addresses of more than 45 elected officials, including information on Hortman. Information on elected leaders from other states and abortion providers was also found in the notebook, as well as detailed notes from surveillance excursions the suspect allegedly conducted on potential targets, Thompson said.

While the suspect slipped away, Burley said the police encounter thwarted the suspect's apparent plan to kill more politicians.

"Had they not foiled the plan -- which essentially took his vehicle away from him, [as well as] all his maps, all his names and weaponry -- I would be very scared what it would have looked like over the next few hours had we not done that," Burley said.

At the time the sergeant sent officers to Hortman's home, he was only aware of the shooting at Hoffman's home and that his intuition as a veteran law enforcement officer told him to check on Hortman, Burley said.

Thompson said that between the time the suspect allegedly shot Hoffman and his wife and went to Hortman's home, Boelter allegedly went to the residences of two other state lawmakers, one in the Minneapolis suburb of Maple Grove and the other in nearby New Hope.

The state representative in Maple Grove was on a family vacation when Burly was captured on video ringing the politician's doorbell at 2:24 a.m., Thompson said.

After leaving Maple Grove, the suspect drove to the state senator's home in nearby New Hope, Thompson said. After arriving at the senator's street and parking, the suspect was interrupted by a New Hope police officer who was sent to the house as a precautionary measure.

The New Hope officer drove up alongside the suspect's vehicle, rolled down her window and attempted to speak to the person she believed was an officer inside, Thompson said. But the person sitting in the vehicle didn't respond and stared straight ahead, according to Thompson. The New Hope officer continued to the state senator's home and waited for other officers to arrive. By the time backup officers got there, the suspect had driven away, according to Thompson.

Sen. Ann Rest, D-Minn., publicly confirmed on Monday that it was her home in New Hope that the suspect was parked nearby.

"I am so grateful for the heroic work of the New Hope Police Department and its officers. Their quick action saved my life," Rest said in a statement.

During Monday's news conference, Thompson praised the proactive measures taken by the New Hope and Brooklyn Park police.

"It really is remarkable, he [the suspect] went to four houses and in two of them encountered law enforcement," Thompson said.

Big mistake by the suspect

On Saturday afternoon, Drew Evans, superintendent of the Minnesota Bureau of Criminal Apprehension, named Boelter as the suspect in the shootings in Champlin and Brooklyn Park, and asked for the public to report any sightings of him.

As officers from multiple law enforcement agencies fanned out across the state searching for Boelter, the suspect made a key mistake by trying to go to his farm in Green Isle, Minnesota, where police were already looking for him.

Authorities have yet to say what evidence they found at Boelter's farm or comment on why he would take such a risk in trying to get to his property.

Eagle-eyed neighbor

Wendy Thomas was on the phone with her father around 8 p.m. on Sunday when she saw someone in a field as she was leaving a friend's home in Green Isle in a rural part of Sibley County.

Thomas watched as the person reached a culvert and squatted, she told Minneapolis ABC affiliate KSTP.

"I was like, 'Dad, that's somebody,'" Thomas said. "He said, 'Hang up and call somebody.'"

Thomas told KSTP she got in her car and drove to the end of her road, where she flagged down a law enforcement officer driving by.

"I rolled down the window and started waving… He said, 'Is everything OK?'" Thomas said of the officer she flagged down. "I said no, there is somebody here, there is somebody in the culvert."

Boelter was earlier recorded on a trail camera walking about a mile from his farm, authorities said. The video footage, obtained by KSTP, showed Boelter walking through a grassy field carrying a backpack just before 7 p.m.

Soon after Thomas flagged down the law enforcement officer, police swarmed the area.

As residents in the area sheltered in their homes, a law enforcement officer on a loudspeaker ordered Boelter to come out of the field, saying, "We have a warrant. Take a look around. You are surrounded," according to a video taken by a local resident and shared with KSTP.

Authorities said Boelter came out of hiding and crawled to officers, who took him into custody without incident.