The partner of the Colombian immigrant who was fatally shot by an immigration agent in Maine this week urged people not to remember him for the way he died but rather for his unyielding desire to build a good life for his family.

In her first public comments since the shooting on Monday, Karolina Rojas recalled Johan Guerrero, 25, as a tireless worker “who couldn’t stand sitting still,” an adoring partner who treated her like a queen, and a father whose greatest joy was his 3-year-old daughter.

“From the moment he learned he would have a little princess, everything in him changed,” Ms. Rojas told reporters at a news conference on Thursday at a hotel in Biddeford, Maine, tearfully reading from a statement as an interpreter translated.

“He always said that little girl will never lack for anything, and that’s how it was,” she continued softly in Spanish. “From the moment he held her in his arms and held her tiny hand, he never let her go. He always worked so that his gordita, as he called her, would never go without.”

Investigators have not released details of the shooting in Biddeford. But a spokesman for Senator Angus King said this week that the senator had been told by senior officials that Mr. Guerrero was not the intended target of the immigration operation. Mr. Guerrero was in his car just after 7 a.m., as he headed to work.

Benjamin Gideon, a lawyer representing the Guerrero family, said at the news conference that Mr. Guerrero had been working in the United States lawfully. “The Trump administration issued him a permit to work in this country legally,” he said. “And they issued him a Social Security card and a Social Security number.”

“Do we accept the idea that innocent, loving partners and loving and devoted fathers of 3-year-olds can be collateral damage to this government’s policies?” Mr. Gideon asked. “Do we agree that this is just an acceptable cost of doing business?”

The Department of Homeland Security said in a statement on Wednesday that Mr. Guerrero illegally entered the United States on Sept. 1, 2023, via the southern border. “To be clear, work authorization does not confer legal status in the United States,” the statement said.

Like generations of immigrants before him, Mr. Guerrero left his native Colombia to pursue a dream of bigger opportunities in America.

In his hometown, Bucaramanga, a mountainside city of one million people in north-central Colombia, people who knew him described a young man who had distinguished himself at a young age as a hard worker, with a relentless drive to get ahead.

Ricardo Triana, a neighbor who lived down the street and owned a glass and glazing company, remembers how a teenage Mr. Guerrero had pestered him for a job until the older man finally relented.

Mr. Guerrero used his earnings from that first job to buy a bicycle, then traded up for a motorcycle and, eventually, an old white Fiat.

“That guy was a workhorse,” Mr. Triana, 49, said in an interview on Wednesday. “He was focused and he would work doing whatever he could find.”

One of three children raised in a middle-class neighborhood, La Victoria, Mr. Guerrero grew up playing soccer and riding bicycles, friends and neighbors said, and graduated from a secondary school, Nuestra Señora del Pilar, in 2018.

In the neighborhood, dotted with fruit and vegetable shops and modest watering holes blasting vallenato music, he was known as Sebas, an abbreviation of his middle name, Sebastian.

One of his older sisters ventured to America before him, settling in Biddeford, a small, blue-collar city south of Portland. Her move seemed to place Mr. Guerrero’s dreams within reach. Then, after Mr. Guerrero learned that Ms. Rojas was expecting a baby, he became a man on a mission, said Julio Mosquera, a friend and former co-worker — determined to provide the best life he could for his family.

“All he did was work and talk about his little girl,” Mr. Mosquera said.

Mr. Guerrero sold his car and, with Ms. Rojas, set up a grill on the corner of his parents’ street, neighbors said, selling beef skewers to save money for the move. Mr. Guerrero traveled to the United States first, in 2023. Within his first year in Maine, he had saved enough money to pay for his partner and baby daughter to join him.

He routinely worked 12-hour days, first as a cleaner at a veterinary clinic and then as a food delivery driver at night, said Mr. Mosquera, who last spoke to him on Saturday.

The news that Mr. Guerrero had been killed rippled down his street in Bucaramanga at lightning speed on Monday. Neighbors of his parents said they heard his mother cry out in shock in their second-floor apartment. They rushed to offer comfort but found her inconsolable.

Camilo Bayón, 24, who grew up playing hide-and-seek with Mr. Guerrero, said he was still struggling to believe his friend was gone.

“I don’t know if I’ve cried myself dry or if I’m empty,” Mr. Bayón said. “All I can say is that this hurts incredibly.”

More than 2,500 miles away in Maine, Ms. Rojas described her own emptiness, and her struggle to find a way to explain Mr. Guerrero’s absence to their daughter.

“He always said I was his life, and that he dreamed of a whole lifetime with me,” she recalled on Thursday. “He always told me, ‘Until we’re little old people.’”

Mr. Guerrero had a joy that was contagious, she said, especially when he was indulging the 3-year-old with chicken nuggets and fries, or playing with her in the park.

“He would always look at her and say she’s getting so big and beautiful, and the tears would come to his eyes,” Ms. Rojas said. “I don’t have the strength to tell her Papa isn’t coming.”