The killing of 8-year-old Chelsea Cromartie generated a powerful response from the D.C. police. While homicide investigators worked the streets, teams of officers passed out fliers and set up roadblocks in an exhaustive search for witnesses. Top officials appealed for help and boosted a reward for clues.

Aided by a tip, police identified two suspects within a week of the Northeast Washington shooting. The police work drew praise from neighborhood leaders and fulfilled a promise made by top officials that they would catch whoever fired the bullets that missed their targets and flew into the home that Chelsea was visiting May 3.

Not every homicide in the District commands so much attention. In a city that is struggling with one of the nation's highest homicide rates, police must make difficult decisions about how to deploy resources. Witnesses frequently are difficult to locate and, even when found, sometimes refuse to give information. This year, police say, the homicide clearance rate is less than 60 percent.

Commanders and former top officers said they must assess a variety of factors after each killing -- from the type of crime and the victim's history to how readily witnesses will help them. Although police insist that they investigate each homicide thoroughly, they said they often feel like battlefield surgeons performing triage.

The choices inevitably add to the grief of family members of victims whose crimes go unsolved.

Some D.C. Council members and victims' rights advocates said the department should use Chelsea's case as a model for future investigations by adding homicide detectives and offering bigger rewards. It is not fair, they said, that some slayings get more attention than others.

"Should one murder be more important than another murder?" asked Kenneth E. Barnes Sr., whose son was slain in September 2001. "I don't think so."

Barnes's son, Kenneth Barnes Jr., 37, was a well-known shop owner on U Street NW who was killed during an apparent robbery attempt. The killer was sentenced to prison in that case. Barnes has since attempted to aid the families of other victims by creating a nonprofit group called Reaching Out to Victims Together.

Kami Emanuel's fiance, Derrick Taylor, was killed about 6:45 a.m. May 9 in Northeast Washington. She said detectives appear to be working hard but wondered why they have not raised the reward, now up to $25,000, in the case.

"A murder is a murder," said Emanuel, 27.

Police Chief Charles H. Ramsey said the department takes every killing seriously. He said he did not hesitate to focus so heavily on Chelsea's case. The third-grader was shot in the head while watching television in her aunt's home, and her aunt was wounded by another of the stray shots that came through the living room window.

The community was outraged, Ramsey noted, with scores of people attending a candlelight vigil and dozens calling police with tips. The killing became the lead story on local television broadcasts and was front-page news. Ramsey said police believed that they had a solid chance at solving the case if they acted aggressively, and they did not want to let any leads slip past them.

"It was hot," Ramsey said. "Not every case generates that kind of interest."

The nature of the crime and Chelsea's age attracted community attention and sympathy that helped fuel the urgency to solve the case. Detectives and other officers also could imagine their own daughter dying in such a senseless way, police officials said.

"Some cases, you don't have to ask guys to come forward and work," said lawyer W. Louis Hennessy, former commander of the D.C. homicide unit. "These are unique cases. The guys take it upon themselves to go the extra mile."

Last summer, as the department was under pressure as homicides spiked, Ramsey raised the rewards offered in homicide cases from $10,000 to $25,000 per victim. In Chelsea's case, the department swiftly doubled it to $50,000. The amount eventually reached $75,000 after a private contribution.

The donation came from William E. Schuiling, a Michigan resident and chairman of Brown's Automotive Group, which has dealerships in the Washington area. He pledged $225,000 more to help police solve other slayings of children. "Nothing is more sickening or despicable to me as when someone kills an innocent child," he wrote in a letter to Ramsey.

Ramsey said officers and investigators were added to deal with the high volume of calls and leads about Chelsea's slaying. One crucial tip helped lead to the arrests of brothers Raashed and Ricardo Hall, who were charged with first-degree murder.

Community pressure and an all-out blitz by police are hardly guarantees that cases will be solved quickly. It took police nearly two years to solve the 1997 triple slaying at a Starbucks coffee shop in Georgetown. It took nearly a year to make arrests in the April 2003 slayings of three employees at Colonel Brooks' Tavern. And the slaying of former intern Chandra Levy remains unsolved three years after she disappeared.

Police received scores of tips in all three of those investigations. But such community interest in homicides -- the city recorded 248 killings last year -- is not common, detectives say.

Last year, Ramsey released a surveillance tape that showed a daylight killing at a Northeast Washington gas station -- and witnesses doing nothing to report the crime or assist the victim. The killing of Allen E. Price remains unsolved.

Police detectives tell countless stories about uncooperative witnesses, even relatives who saw their loved ones killed but won't point out the killer. In some cases, witnesses fear they will be targeted. Police and prosecutors said that witness intimidation has been a long-standing obstacle to solving crimes.

Also, police said, friends of some victims would rather avenge killings on their own than help officials.

Investigators said they often identify suspects only to stumble when trying to persuade witnesses to come forward.

Two days before Chelsea was slain, D.C. police were called to investigate a midafternoon killing in a Southeast Washington housing complex. Detectives quickly discovered evidence that pointed to a gun battle: Shell casings from at least four weapons littered the street.

Scores of residents watched as technicians and detectives scouted for evidence, recalled Lt. Guy Middleton of the violent crime unit. Yet despite the public nature of the gunfight in the Barry Farm complex and detectives canvassing and recanvassing the neighborhood, no one came forward with information, Middleton said. The slaying of Antonio Blakely, 18, who lived in another part of town, remains unsolved.

"It's frustrating," said Middleton, a veteran homicide investigator and supervisor. "The people continued to stand there when the police arrived. All were out there when it happened."

D.C. Council member Kathy Patterson (D-Ward 3), chairman of the Judiciary Committee, said police could do more in solving homicides. She said officials should add more detectives and resources for investigations. "Every case should have the kind of tenacity and commitment" that the Chelsea case did, Patterson said.

But some former police officials said that certain killings -- such as Chelsea's -- demand more attention.

"There is something exceptional about this homicide," said Isaac Fulwood Jr., the District's police chief from 1989 to 1993, comparing the handling of the case to how officers work round-the-clock to solve the killing of fellow officers.

"You can't shoot 8-year-old girls sitting in their house watching television," Fulwood said. "Everybody was fired up by this little 8-year-old girl. I don't care what you have to stop doing, you have to get on this homicide. That is the reality of it."

Staff researcher Bobbye Pratt contributed to this report.