Inside, many who packed the small, windowless church in Corona wore uniforms, both official and more personal, that reflected the diverse passions pursued by Mr. Polanco.

There were the men and women in military dress, a testament, friends said, to the pride he felt in his four years of service in the Guard. There were others, in the matching black leather vests of a local car club, who spoke of how Mr. Polanco tinkered with an old Honda before saving enough money working at a dealership to buy a new one. Several friends wore T-shirts with his likeness, or sweatshirts with his nickname and a somber message: "R.I.P. Sparxxz."

Mr. Polanco drew tattoos and loved music; he avoided trouble and aspired to join the Police Department. He worked hard at several jobs, friends and family said, and still jumped at the chance to do favors for those in need.

"He was always there to help," his mother, Cecilia Reyes, said through tears as she stood near the coffin, which was covered by a flag. "He's my prince."

Behind her, men and women in uniform sat in a row facing the congregation. Early in the 90-minute service at the Eternal Love Baptist Church, two officers from the National Guard awarded Mr. Polanco a medal for Army achievement and promoted him posthumously to sergeant. The church erupted in applause.

"I want my brother to rest in peace," said Sgt. Jonathan Polanco, Mr. Polanco's brother, who is in the Army. "But along with peace, you need to have justice."

The Rev. Al Sharpton, who delivered the eulogy at the request of Mr. Polanco's family, denounced the actions by police officers that led to Mr. Polanco's death. He appeared to reflect the sad exasperation many felt that a young man who seemed to do things right had died from police gunfire.

"He was as right as you could get," Mr. Sharpton said.

Mr. Polanco was killed on Oct. 4 when Detective Hassan Hamdy, a decorated former Marine and 14-year veteran of the Police Department, fired a single bullet during an early-morning traffic stop on the Grand Central Parkway near La Guardia Airport.

The killing tore at already raw tensions between the police and the city's minority communities. It also followed several high-profile police shootings involving civilians, including one near Times Square and another outside the Empire State Building. But unlike those and other recent police shootings, police officials have not offered a clear explanation of how Detective Hamdy came to shoot an unarmed man.

On Thursday, Ms. Reyes and her lawyers met with the Queens district attorney, Richard A. Brown, pressing for a full investigation and, as Ms. Reyes said, "no cover-ups."

"I just want this to be done the right way," she told reporters.

Before the shooting, the police said, Mr. Polanco was driving erratically, twice cutting off a pair of trucks carrying officers from the Emergency Service Unit who had just finished executing a warrant in the Bronx.

Outside the church on Friday, bells sounded as mourners filled the sidewalk. A line of service members formed to salute the coffin silently as photographers craned for a view. Across the street, television reporters filed their stories and the news trucks pulled away.

A caravan of cars, some bearing Mr. Polanco's nickname in white writing on their windows, moved on to the Maple Grove Cemetery in Kew Gardens, Queens. There, Mr. Polanco was interred in a service that included ceremonial military gunfire and the presentation to Ms. Reyes of a folded American flag.

This article has been revised to reflect the following correction:

Correction: October 12, 2012

An earlier version of this article misstated the name of a survivor of Noel Polanco and their relationship. He is Jonathan Polanco, not Juan Carlos Polanco, and he was a brother, not a stepbrother.