After they graduated from Instituto Superior Técnico and moved abroad, Loureiro lived up to his potential, for as long as he lived. He became a husband, a father of three, and a world-renowned physicist at the Massachusetts Institute of Technology, where he was trying to replicate the energy of the sun.
Valente dropped out of his PhD program at Brown University, then disappeared into darkness and isolation. For the last decade of his life, not even his parents knew where he was.
Their lives, once so closely interwoven, diverged for 25 years. Then, one Monday night in December, they clashed violently back together. Two days after Valente carried out a mass shooting at Brown, he drove to Loureiro’s home in Brookline and shot him in the lobby of his building.
From the Portuguese countryside to New England’s most elite academic institutions, no one who knew the men could understand. By all accounts, they hadn’t seen each other in decades. They hadn’t been particularly close in college. What had driven Valente? How damaged does a person have to be to commit such crimes?
“Sometimes it seems like a lie,” said Bruno Soares Gonçalves, president of Técnico’s Institute for Plasmas and Nuclear Fusion. “It’s difficult to imagine how this could have happened. I can’t make sense of it.”
Two months after Valente took the lives of two Brown students and Loureiro, people who knew the two men are still trying to understand. Only now have they begun to piece together old memories, recalling small moments that could help explain the unimaginable.
Authorities haven’t named a motive. But in interviews with the Globe, those who knew Valente describe a man frustrated at a world that failed to recognize his precocious talents. Valente graduated Técnico with the highest grades of his class, but it was Loureiro – whose grades were average – who went on to lead his field, earning acclaim from his peers, his students, and even the US president.
Nuno and Cláudio, Cláudio and Nuno. Their lives, now tragically intertwined, tell a story of mental illness, grievance, and grief.
The Globe spent two months reporting this story from the United States and Portugal, traveling to the campus where the two met in Lisbon, Valente’s hometown in Entroncamento and his high school in Torres Novas, and Loureiro’s hometown in Viseu. This article is based on dozens of interviews in English and Portuguese and dozens of pages of public records in both countries. The families of both men declined to be interviewed.
No one saw it coming. The people of Entroncamento, his hometown, remembered Valente as a kind, sweet boy; his former colleagues described a brilliant if odd man. Loureiro’s friends imagined a successful and happy future for him — grandchildren and scientific discovery and, maybe one day, that Nobel Prize. No one could imagine one man would rob the other of that future.
* * *
They arrived on Técnico’s campus in Lisbon in 1995. In his photo as a college freshman, Valente wore a yellow plaid shirt and the shy smile of an awkward teenager. In his photo, Loureiro smiled with his mouth closed, a confident young man looking to the future.
The students came from all over the country and were perceived as the best of the best. Técnico is Portugal’s MIT, and the physics program was the crown jewel. The professors were rigorous, and the competition palpable.
Valente and Loureiro started with the same foundational courses. In a large lecture hall, they sat on wooden chairs covered in doodles, song lyrics written in whiteout. That’s where they got through algebra and calculus.
In a small cohort that was almost all men, Valente and Loureiro went to the movies, hung out at local bars, and attended dinner parties, classmates recalled.
Soon Valente started to gravitate toward theoretical subjects, such as electromagnetism and quantum mechanics, spending time in the world of ideas. Loureiro was drawn to applied physics, the physics of the real world, such as thermonuclear fusion.
In some classes, students helped each other, studied together, and collaborated on assignments, professors said. In others, they were on their own. Grades, after all, would determine who got into competitive PhD programs in the United States, which many looked to as the ultimate goal.
“They were the gods of their high schools. Then they arrive here and find 100 other guys who are exactly like them,” said João Seixas, a physics professor who taught Valente and Loureiro. “For many students, this is a problem because they realize that even with a gigantic effort, they only achieve average results.”
Both took two of his courses. Neither really stood out at the time.
“They weren’t very different people,” Seixas recalled.
Over the years, Valente earned higher grades than Loureiro and the rest of their classmates. He eventually graduated with the equivalent of an A-plus. Loureiro earned the equivalent of a B-plus.
Loureiro was hard-working yet humble, not particularly competitive. His former classmates often described him as “pacato” — peaceful. He seemed to already know there was more to life than grades.
Valente was equally hard-working, yet visibly competitive. He showed up to classes ready to speak about any subject with authority, seemingly having read all there was to know in advance. No one could deny he was exceptionally intelligent.
At times, Valente seemed arrogant. But arrogance wasn’t uncommon in that crowd.
A former teaching assistant in one of his classes, Filipe Moura, wrote online that Valente constantly made a point of showing his classmates he was the smartest one, sometimes getting into loud, pointless arguments that made some uncomfortable. But his classmates didn’t see anything unusual, they said.
“They were students with a big ego,” Gonçalves, of Técnico’s plasmas institute, said of the student body. “I think all of us were kind of nerds or somewhat peculiar.”
At the time, Gonçalves said, academic competition didn’t seem like something to worry about.
* * *
After Técnico, Valente and Loureiro moved out of Portugal to begin PhD programs: Loureiro in England, and Valente in the United States.
Valente had long dreamed of attending MIT, but scored poorly on standardized admissions tests, according to former classmates. He was accepted into Stony Brook University and Brown, and chose the Ivy League option.
Eager to start conducting research, Valente found the physics courses too easy. He tried to persuade two professors to become his advisers before he took qualifying exams, and they refused.
“He didn’t have the patience for that process,” said Scott Watson, who described himself as Valente’s only friend at Brown and is now a physics professor at Syracuse University. “He thought it was beneath him to have to take the qualifying exam.”
Valente complained about Providence, about the physics program, about American food. When they went out to eat, it had to be at a Portuguese place, Watson said. Valente often ranted about the lack of fresh fish in the city’s restaurants.
Only recently did Watson remember that Valente once complained about Loureiro by name. It didn’t stand out at the time, mixed in with the other frustrations. Valente claimed he “got screwed over” when Loureiro received a higher grade than him in a course at Técnico.
“He didn’t think it was justified,” Watson recalled. “He felt he was the best in the class, and he didn’t get what he deserved.”
Valente couldn’t accept someone he perceived to be his inferior receiving a higher grade. He had to be number one, at all times, at all costs.
At Brown, Valente was “by far the best graduate student in our class,” Watson said. “I don’t like the word genius, but he was.”
Even still, Valente started picking fights with classmates. Watson said he often called a Brazilian classmate a “slave,” displaying an ugly bias against people from Portugal’s former colony.
“Every time he’d show up for work, Cláudio would say, ‘Hey, the slave is here to work today,’” Watson said. Once, Watson had to stand between the two men to prevent a fist fight.
At some point in the first year of the five-year program, Valente stopped showing up for classes. By the end of the year, he had decided to leave. During their last dinner at the Portuguese restaurant, Valente told Watson that Brown had nothing more to teach him.
After dropping out, Valente left a message in an online forum for Brown physics students, placing the blame on others.
“!?!HAPPY NOW!?! OK! I am back home and dropped Brown’s Physics Ph.D. program permanently,” he wrote in May 2001. He added in Portuguese: “And the moral of the story is: the best liar is the one who manages to deceive himself. These people exist everywhere, but sometimes they proliferate in the most unexpected places.”
Back in Lisbon, Valente returned to the apartment building he lived in throughout college, a 15-minute drive from Técnico’s campus. The three-bedroom apartment, located in the modest Olivais neighborhood, was a gift from his parents. Living alone on the second floor, he got a job as a programmer in the IT department of a technology company.
It was around this time that Valente began shutting out his parents. His mother and his father drove an hour to Lisbon almost every week, but when they knocked on his door, he refused to open it. The couple eventually befriended Valente’s neighbors, desperate for information.
Often, his mother hid somewhere around the building just so she could lay eyes on her son, even if only for a few minutes.
“He ran away, hid,” said Teresa Ruas, who lived a floor below Valente. “His parents suffered a lot, because they would come to see him and he never wanted to see them. He rejected them.”
Ruas saw Valente only when he entered or exited the building, or ate at a nearby food court, where he spent hours on his laptop. He always avoided interactions with other people, she recalled. She never saw him bring friends or dates home. He seemed like he was running away from something, she said.
Once, around 2010, his parents hadn’t heard from him in such a long time that they feared he had killed himself. They called the police. Firefighters came, broke the windows to enter the apartment, and found no one home, Ruas recalled.
After that, she said, “He got even more rebellious toward his parents.”
Valente’s mother used to call Ruas crying, and eventually said her son had a “mental problem,” but he refused to acknowledge it or seek help. She never elaborated on what the problem was.
At work, Valente shared nothing about his personal life. Colleagues said he was kind, quiet, and helpful — a talented programmer able to solve any problem.
“He was a special person. He was an extraordinary professional,” said Sérgio Bastos, who worked with him starting in 2006.
After the two finished working closely on a project, Bastos wanted to remain friends, but Valente wasn’t interested, he recalled.
Lately, Bastos has also been thinking about how Valente sometimes made disparaging comments about his former Técnico classmates, clinging to a grudge more than six years after they had graduated.
“He had commented that his work had been stolen,” Bastos said. At Técnico, it was “normal” for others to use his work without giving him credit, Valente ranted.
In 2013, when Valente was 36, his 22-year-old second cousin died in a car accident. He attended the funeral, but refused to speak with his parents.
Not long after that, he abruptly resigned from his job and sold his apartment. His parents never heard from him again.
* * *
As a graduate student at Imperial College London, one of the world’s top science universities, Loureiro dove into his research. He published his first scientific article after just one year; dozens more would follow. His 2005 doctoral thesis, on a phenomenon called magnetic reconnection, solved a decades-long mystery, reorienting the entire field. He was still in his 20s.
Loureiro’s career took off after that. He worked at Princeton’s plasma laboratory, then England’s national laboratory for fusion energy, building a body of research about magnetic reconnection.
His life wasn’t without its challenges. During his time at Imperial College, he lost his father to sudden illness. Loureiro visited his family in Viseu as often as he could, and remained close to his mother and younger brother, friends said. He and his childhood friends caught up almost every Christmas.
In 2009, Loureiro returned to Portugal to work at his alma mater, Técnico, a triumphant homecoming. During the seven years he spent in Lisbon, Loureiro and his wife welcomed two of their three daughters.
For at least four years, Valente was living just three miles away from Loureiro at the university, though it’s not clear whether the two ever crossed paths.
Loureiro’s research soon caught the attention of the United States’ most prestigious institutions. In 2016, he accepted an offer to teach at MIT.
Just days before leaving Lisbon, Loureiro had lunch with Gonçalves, the president of Técnico’s plasmas institute, who had become a dear friend.
At a restaurant near campus, the two talked and joked about Loureiro’s big career move. Loureiro was funny, with a refined, “British-like” humor, Gonçalves recalled.
“I remember joking with him, ‘Are you ready for the culture of cheerleaders and American football players?’” Golçalves said, chuckling. “It’s all different from our culture.”
The move to MIT, and to a new home in Brookline, was exciting for the whole family. He found the MIT community inspiring.
“Before you’ve experienced it, I don’t think you quite understand the type of place it is,” he told an interviewer in 2017. “It’s fascinating to be here, surrounded by so many amazing people.”
Loureiro was well known in his neighborhood near Coolidge Corner, often seen with his family or playing in pickup soccer games. His neighbors knew him as a funny, down-to-earth dad.
He was popular among MIT students, too, the type of professor who wrote every equation on the board, rather than having students read them from textbooks. His students loved that about him. He was recognized with awards for outstanding teaching in 2020 and 2022.
“I took every class Nuno taught, even when not required, because he was a tremendous teacher, and I knew I would learn and laugh a lot,” Henry Wietfeldt, a graduate student, wrote in a MIT tribute.
In 2024, MIT named Loureiro director of the Plasma Science and Fusion Center, putting him in charge of a 150,000 square foot laboratory – one of the largest at the university – an annual budget of $45 million, and more than 250 researchers, staff, and students.
He was eager to take on the challenge. “It’s the dawn of a new era with burning plasma experiments,” Loureiro told MIT News at the time. As soon as 2026, he hoped, the lab would create a fusion device to produce plasma that yields more energy than it consumes.
At 47, Loureiro was on top of the world. Interest in fusion science was at an all-time high. His research had brought his field closer to the dream of clean, near-limitless energy. In January 2025, President Biden presented Loureiro with the government’s highest honor for young scientists, the Presidential Early Career Award for Scientists and Engineers.
Most days, colleagues recalled, he walked into the Plasma Center wearing a smile. Loureiro was respected for his scientific achievements, but he was also beloved.
In a speech in 2018, Loureiro gave a hint as to how he defined success in life and academia. For him, it wasn’t about keeping score. “You get credit for some you don’t deserve. You don’t get credit for some you deserve,” he said. “In the end, it averages out.”
He spoke about a colleague, a man he admired. “He is known for being an absolute genius,” he said, “but the reason we celebrate him is because he’s a nice person.”
* * *
For years, Valente was nowhere to be found.
After he left his Lisbon apartment in 2013, former classmates and colleagues stopped hearing from him. He apparently had no social media presence. His family didn’t know if he was in Portugal or abroad, dead or alive.
In 2017, a year after Loureiro was hired at MIT, Valente also made his way to the US, obtaining legal residency through a visa lottery. He briefly lived in Nevada, public records show, and then moved to Florida.
What he did in Miami from 2017 to 2025 remains a mystery. He did not leave any trace in public records or online that would suggest a job, a relationship, or a tie to the city. He became a sort of ghost. No one seemed to know him or notice his moves.
But by Thanksgiving 2025, the two men who seemed impossibly far apart were mere miles from each other.
Loureiro was in Brookline, celebrating the holiday with the Konieczka family, close friends. In Boston, Valente checked into a hotel room.
The following Monday, Dec. 1, Valente rented a gray Nissan Sentra and drove to Brown. For the next 12 days, authorities say, he stalked the Barus & Holley building, where decades earlier he had abandoned his physics career. He paced the hallways, peered into classrooms, and once ducked into a bathroom to avoid being seen, a Brown custodian told authorities. Valente lurked outside Room 166.
As undergraduates studied for their final exams, Valente was preparing for something else. On Saturday, Dec. 13, he burst into the Barus & Holley building and opened fire. In Room 166, he killed two students — MukhammadAziz Umurzokov, a freshman who wanted to be a neurosurgeon, and Ella Cook, a sophomore who excelled at piano and French — and injured nine more before he escaped on foot down Hope Street.
With a mass shooter on the loose, panic flooded Providence. Final exams were canceled, and students fled campus the next morning. No one could find the suspect; no one yet knew it was Valente they were searching for.
Two days after the Brown shooting, as FBI agents rummaged through the bushes in Providence for any clue about the shooter’s identity, Valente was already in Massachusetts. He spent that Monday, Dec. 15, driving around Loureiro’s neighborhood in Brookline.
It was a normal day for Loureiro: He biked to work, oversaw exams, attended a meeting. His mother-in-law was visiting from Portugal and one of his daughters was home from college. That evening, he watched a movie with the girls while his wife attended a dance class.
By 8:30 p.m., at his three-story condo building in Brookline, Loureiro and his wife were in the kitchen, while two of his daughters played cards in the living room. The doorbell rang and Loureiro answered it in his slippers. In the foyer stood Valente, dressed like a delivery man and carrying a cardboard box.
It had been decades since the men shared a classroom. In the years since, Loureiro had the kind of career Valente felt entitled to, stewing in a resentment that put his failures on others. At least once, he had blamed Loureiro by name. Loureiro was everything Valente failed to become.
Now they were in the same room, and Valente had a gun in his hand. He shot Loureiro repeatedly, in his legs, his chest, his abdomen. Then Valente fled.
Loureiro’s daughters heard him scream. Upstairs, Louise Cohen was lighting a menorah candle when she heard the gunshots. She found Loureiro lying on his back and called 911.
As Loureiro was rushed to Beth Israel Deaconess Medical Center, Valente drove an hour north to a storage facility in Salem, N.H., where he had been renting a unit. That night, he recorded four videos of himself talking — rambling treatises that revealed his deep sense of grievance, in which he confessed to the crimes and showed no remorse.
He said nothing about Loureiro but complained at length about a pain in his eye, the result of a shell casing that hit him while he was shooting. “Honestly, my only regret is this thing in the eye,” he said, according to a transcript.
“I am not going to apologize, because during my lifetime no one sincerely apologized to me,” Valente said. “Let’s see if I’ve got the balls to do this to myself now.”
In the morning of Dec. 16, Loureiro died at the hospital. That evening, Valente shot himself dead in the storage unit.
***
At Técnico, the hilltop campus where the men first crossed paths, some students already knew of Loureiro as a famous alumnus. Physics professors honored him with a moment of silence after his death.
No current students had ever heard of Valente before he killed Loureiro.
In the days after the shooting, people placed flowers and candles at the steps of Loureiro’s home in Brookline, and around the gates on Brown’s campus. Hundreds gathered for vigils in the cold to honor the dead. MIT established a memorial scholarship fund in Loureiro’s name, to help future students.
In Viseu, Loureiro’s hometown, the municipal assembly voted unanimously to honor him. When his high school friends gathered around Christmas, they mourned. It was their first reunion without him.
“His family, both here and abroad, were peaceful and friendly people,” said João Paulo Gouveia, a high school classmate who attended the gathering in December. “We were all very sad trying to understand what had actually happened. What led someone to go to another person’s house and murder them?”
In Entroncamento, Valente’s parents received word of their son for the first time in more than a decade. On the television news, they saw a photo of him next to the word “killer.”
The couple stopped going to local cafes and businesses, isolating themselves. In the small town, Valente was a frequent topic of conversation. They stopped opening their front door and picking up phone calls. Neighbors said they were nowhere to be found.
On Jan. 16, a month from the day Loureiro died, dozens attended a Mass at an old Catholic church in Viseu. “May his soul rest in peace,” Loureiro’s childhood friends told his mother. The mourners prayed, cried, and grieved together.
In Entroncamento, Valente’s ashes were buried near his grandparents. His parents held a private ceremony — just five people. In a sprawling Catholic cemetery full of grand mausoleums and headstones draped in flowers, Valente is buried in an unmarked grave.
Brian MacQuarrie of the Globe staff contributed reporting.
Correction, Feb. 19: A previous version of this story misstated which relative was visiting the Loureiro family on Dec. 15. In fact, it was Loureiro’s mother-in-law, not his mother.
Marcela Rodrigues can be reached at marcela.rodrigues@globe.com.