Georgetown, Guyana — When Officer Randolph Holder forgot to call his grandmother here, she fretted. She would go to the local Internet cafe to check up on him, only to hear him wave away her worries from the other end of her cheap online connection. He would lament only that he could not arrange his clothes as neatly as his grandmother did.

The call the grandmother, Elizabeth Lovell, got Tuesday night was far graver. Her grandson, a widely respected New York Police Department officer who followed three relatives into law enforcement work, had been shot in the head and killed on the job in East Harlem.

The visit he had planned to his home country this Christmas was no more, and the fish his grandmother looked forward to frying for him no longer a concern. The cash gifts for her birthday and Mother’s Day would end, and the promises Holder had made to bring a little brother to the United States would fade.

“I could have died,” Lovell said Wednesday, clutching a photo of her grandson in uniform. “The phone fell out of my hands, and I had to go sit in a corner. I felt weak, weak, weak. Like I didn’t know what to do.”

Holder’s killing not only plunged his adopted city into mourning but also reverberated across continents, reflecting the immigrant origins of many who wear the shield of the New York Police Department. He was a source of pride and promise here, an officer on the path to becoming a detective on a police force roughly 10 times the size of Guyana’s, where his father, grandfather and great-uncle had all served.

The tales of those men’s police work planted a dream for Holder of going into the family trade.

“He loved the stories,” a cousin in Queens, Stacey Lawrence, 29, said. “And his father was his hero, and you want to follow what your hero does.”

After leaving Guyana and joining his father in Queens 12 years ago, he took a job as a security guard at a Toys “R” Us store and then entered the New York Police Academy, joining the department in 2010 over the objections of some relatives who wanted him to continue his education.

It was the culmination of an often painful journey. His mother had died of cancer when he was 17. His family home in Lodge, a struggling suburb of the capital city of Georgetown, was destroyed by fire in May 2002. His brother, Kelon Noel, remembered how Holder took care of him, even helping to wash his clothes by hand.

“He was more than amazing,” Noel, 26, said in an interview in Georgetown. “Words can’t describe the person he was; he was so loving to me.”

Holder, 33, amassed 125 arrests as he rose to an elite plainclothes anti-crime unit in a dangerous pocket of northern Manhattan. He won department citations for excellent or meritorious police duty on six occasions. He wore badge No. 13340.

“He always wanted to be a policeman, and that’s what he did,” his father, also named Randolph Holder, told reporters outside his Queens home. “He delivered his duties diligently with pride, lots of principle and discipline.”

The cries of mourning relatives occasionally seeped out from the small, white-shingled house, where a string of local political leaders, clergy members and police colleagues came to pay respects.

Relatives said Holder always worked hard not to bring the tumult of life as an officer back to family gatherings, calling on a reserve and strong will that he shared with his father. They knew he was nearby by the heavy scent of his cologne. He was the designated DJ at family barbecues, toting his small speaker system to relatives’ backyards. His parties always lasted until 5 a.m.

“He was always the life of the party,” a cousin, Claude Sultan, who is from Trinidad and Tobago, said.

Holder’s tastes reflected his heritage as well as the diversity of his Queens neighbors, with Calypso, reggae, hip-hop and Spanish music often blaring from his portable speakers.

But fears of gun violence in East Harlem had begun to weigh on him before his killing.

“It was something that he loved to do,” an aunt, Sherry Holder, said. “But recently he was saying that the area in which he worked was a very dangerous area, where everybody owns a gun. And he felt like his life is threatened.”

Sultan said it was just that violence — and the dread it spawned in black families across the city — that drew him into police work. He came of age in an area of Queens where many residents have friends who have been shot, as Sultan said he did.

When one of Sultan’s friends was killed around Thanksgiving last year, Randolph Holder offered him both comfort and some caution, as he often did.

“Still, at the end of the day you’re telling me to be careful, but you’re putting yourself on the line,” Sultan, 22, said.

A senior police official said Holder was on the way to becoming a detective.

“Good evaluations,” the official said of his record, speaking on condition of anonymity to discuss personnel matters. “No disciplinary history. He had medals. He was a very good officer.”

Neighbors who lived beside his home in Brooklyn, where he had moved several years ago, recalled his waking up early to shovel their snow and dragging their trash cans to the curb on pickup days. They said a girlfriend visited frequently. His father said he also had a 16-year-old daughter.

On a fence outside the Wagner Houses, a public-housing project near where the shots were fired that drew Holder’s attention, someone had scrawled on a poster: “Know that you and your kind is appreciated — The Community.”

For friends and relatives in Guyana, his path to New York police officer appeared all the more unlikely, and his killing struck an incalculable blow.

“We came up rough; we always tried to make good of every little thing,” said Quincy Christian, a close friend who used to walk to school through burial grounds with Holder. “Everything we acquired, we shared equally.”

He was denied a visa on his first attempt to travel to New York, his grandmother said. On a second attempt, she added, he got to the U.S. Embassy at 3 a.m., four hours before a scheduled appointment, to make sure he would not miss it.

Noel remembered his brother’s promise to take care of him financially until he could make the same trip himself. Since he got the news, he said, he had developed a migraine headache that “ain’t going away.”

Relatives said the family planned to send Holder’s body back to Guyana for burial, to the town he used to speak about when friends expressed concern about his safety as a police officer.

“He always used to say he was from Lodge,” Christian recalled, “so he could survive anything.”

Kate Pastor, Liz Robbins, Rick Rojas, Kirk Semple and Alex Vadukul contributed reporting.