As Austin Jeffrey Boutain stepped out of an elevator at Salt Lake City Main Library Tuesday afternoon, an alert librarian recognized him as the man officers had sought in a massive overnight hunt after the fatal shooting of a University of Utah student.

The librarian greeted Boutain — as he does everyone who visits the third floor — then waited until Boutain was out of earshot and called security, according to City Library Communications Director Andrew Shaw.

Within minutes, security officers apprehended Boutain, who had appeared to be unarmed, in a restroom, Shaw said.

“A big shout out to a librarian,” Salt Lake City police Chief Mike Brown said at a news conference Tuesday afternoon, announcing Boutain, 24, had been taken into custody at about 1:10 p.m.

Brown said Boutain was being questioned and would be booked into the Salt Lake County jail in connection with the Monday night shooting death of 23-year-old ChenWei Guo, an international student at the U. Guo, who is from China, was killed during an attempted carjacking near Red Butte Canyon, police said.

University authorities have declined to say whether Guo was alone in the vehicle when he was shot.

Also Tuesday, University police Chief Dale Brophy announced that Boutain and his wife, 23-year-old Kathleen Elizabeth Rose Boutain, may be connected to a recent suspicious death in Golden, Colo.

Salt Lake City officers had asked Golden police to check on the owner of a green 2000 Ford pickup truck with Colorado plates that Boutain was allegedly driving in Utah.

Austin J. Boutain (Photo courtesy Marion County, Alabama, jail)

When Golden officers arrived at the Clear Creek RV Park, they found 63-year-old Mitchell Bradford Ingle dead inside a trailer, the department said in a Tuesday news release. “Preliminary investigations indicate that the man had been deceased for a few days,” the release said.

There were obvious signs of trauma to Ingle, who had been staying at the RV park on a short-term lease, and the Boutains are considered persons of interest in the case, Golden police said.

The stolen pickup truck was still being sought by Salt Lake City area police on Tuesday.

Events in Utah began at about 8:15 p.m. Monday, when Kathleen Boutain went to the U. campus and reported that her husband had assaulted her while they were camping in Red Butte Canyon, Brophy said. She was being treated for an unspecified injury just before 9 p.m. when Guo was shot, Brophy said.

Kathleen Boutain admitted to police that she was “traveling in a stolen vehicle which contained stolen firearms,” according to a probable cause statement filed with the Salt Lake County jail.

She was arrested Monday night and booked into the jail, where she was being held without bail on suspicion of theft by receiving stolen property and drug possession charges. Police said she had a prescription bottle of generic Ambien that was not labeled and other drug paraphernalia.

Police are still stitching together a timeline of how Boutain got from the foothills above the university on Monday night to the library, at 200 East and 400 South, and how long he had been in the library Tuesday before he was spotted.

Kathleen Boutain

The earliest Boutain could have been in the library is 9 a.m., when it opened, Shaw said. It had closed at 9 p.m. the night before, at around the time of the homicide.

In an interview Tuesday, security guard Johann Gonzalez-Rubio described approaching Boutain in the library’s restroom on the third floor. He said Boutain nonchalantly told him, “Hey man, I just need to use the restroom real quick and then you can arrest me.”

Boutain appeared calm and unarmed, Gonzalez-Rubio said. Because a bystander also was in the restroom, the guard said, he stepped outside to wait for backup to arrive and for the other man to leave. Then he and another security guard went back in together.

“Hey, you got me,” Boutain said, as he knelt down and put his hands behind his back, according to Gonzalez-Rubio.

The Boutains had been in Utah “a couple days,” Brophy said. Their campsite in Red Butte Canyon was located Monday night, Brown said, and police recovered a rifle and ammunition cans. Police were not sure if the rifle was the same weapon used in the U. slaying.

Police and prosecutors from Golden investigating Ingle’s death were expected to travel to Utah on Tuesday to gather more information, which could include interviewing Kathleen Boutain.

(Courtesy, Golden Police Department | Mitchell Bradford Ingle was found deceased in his RV trailer on Monday.)

Boutain reportedly has family in Minnesota and as recently as 2015 lived in the Cincinnati suburb of Millvale, in Ohio, according to Fox 19 TV. The station noted that he entered a guilty plea in May 2015 to “obstructing official business” in exchange for a disorderly conduct count being dismissed.

Fox 19 reported that he had been accused of fleeing police in connection with an unspecified disturbance at Cincinnati’s Good Samaritan Hospital.

Alabama court records system show Boutain was arrested in March in Marion County on drug manufacturing charges, according to WAFF 48 TV in Huntsville, Ala. He also was arrested in February 2016 on charges of theft and attempting to elude in another state. Court records also show he is a registered sex offender who failed to notify officials in Marion County when he moved there in 2016, WAFF 48 TV reported.

.@slcpd Chief Mike Brown discusses details of the search timeline and search effort last night following the shooting @sltrib pic.twitter.com/AmXenxhvlX — Brennan Smith (@BrennanJSmith) October 31, 2017

On Monday night in Utah, the hunt for Boutain initially focused on an area east of Mario Capecchi Drive. Classes were canceled and that area of campus — which includes the school’s main residence halls, medical complex and research buildings — was locked down until about 3 a.m.

Officers from at least eight police agencies, including the FBI, responded to the scene. The hunt included a helicopter, snipers and hundreds of officers who scoured the foothills around Red Butte Canyon.

But the overnight search was called off at about 11:30 a.m. Tuesday, after police said they believed Boutain had outflanked them and escaped the police perimeter.

U. President David Pershing released a letter early Tuesday in which he said classes had been cancelled for the day out of respect for Guo, a pre-computer science major, and because of “the impact this violent event has had on our campus community.”