District police officers make an arrest in September in the Park View neighborhood in Northwest Washington. (Jahi Chikwendiu/The Washington Post)

Frustrated by a surge of robberies on Capitol Hill and other crime, Denise Rucker Krepp posed what she thought would be a simple question: What happens to the thousands of people D.C. police arrest each year?

Turns out it’s anything but a simple question. And it could be an expensive answer.

The Justice Department told Krepp, an advisory neighborhood commissioner for Hill East, that the government doesn’t keep a readily available list of conviction rates. And to compile the five years of data that she requested for all eight wards of the District, along with a breakdown from her neighborhood, it would cost $40 an hour, plus an additional 5 cents a copy.

Authorities also advised Krepp to not expect her information anytime soon. A request judged to be “simple” can take 30 days, officials wrote her. “At this time, your request has been assigned to the Complex track,” the letter said.

Krepp, who has lived on Capitol Hill for 14 years, agreed to pay up to $1,000 of her own money for the information, which she requested under the Freedom of Information Act. The law is designed to help citizens get data and documents from the government.

People in her community agreed to help defray the cost — Krepp has gotten about $200 so far — and she’s holding a “FOIA Cakes Bake Sale” at Eastern Market on Sunday to raise more. Events DC is providing tickets to a Georgetown University basketball game for a raffle, and Dangerously Delicious Pies is donating proceeds from its Sunday sales.

Krepp is a bit of a rabble-rouser — her history of complaints targeting agencies such as Metro and the District’s housing regulatory office has made hers a name officials remember, often with a roll of their eyes. But with the crime issue, Krepp has found a cause that resonates not only with residents fed up about crime, but also with the police chief and the mayor.

City leaders facing a nearly 60 percent increase in homicides and a robbery surge in some neighborhoods have put the blame on repeat violent offenders. Police Chief Cathy L. Lanier has said that more than 10 homicides this year involved offenders released from prison on charges related to previous slayings.

Both Lanier and Mayor Muriel E. Bowser (D) have called for ways to make it easier for the public to track criminal defendants through the complex and often-confusing criminal justice system. Both officials have said the data Krepp is seeking is difficult for them to get as well, and they’re pressing for ways to spread accountability beyond police and to a broader criminal justice spectrum.

Krepp said she has been told repeatedly by prosecutors, “We can’t provide what you’re looking for because we don’t keep it.” She said it’s one thing to track one case through the system, “but that doesn’t give us the bigger picture. Without the bigger picture, we don’t know how cases­ are being prosecuted. . . . Police keep arresting the same individuals. We want to know what happens to them.”

The neighborhood commissioner said she agreed to pay $1,000 because it covers roughly three full days of work. “If they can’t find this information in half a week, we’re in trouble,” Krepp said. “It’s information they should already be tracking.”

The U.S. attorney’s office for the District publishes an annual report that includes statistics for the number of cases­ it receives from law enforcement agencies and the number it decides to prosecute — a process called “papering.” That report for D.C. Superior Court shows that prosecutors were presented with 24,500 new cases­ in 2014 and moved forward on 15,000 of them, including 3,000 felonies.

But the report does not show the outcome of each case, such as how many resulted in convictions, dismissals or acquittals, and what the sentences were. Bill Miller, a spokesman for the office, said an overall conviction rate covering cases­ in the District could be obtained after research. Further breakdowns, either by case or geographic area, could take a long time to compile.

Miller said prosecutors and others from the office routinely attend community meetings — 47 in November — and publish a monthly newsletter called “The Court Report” that contains a synopsis of significant cases­ and list of arrests that are being prosecuted.

But Krepp said the information doesn’t provide the specific data needed to judge whether cases­ are being handled correctly. Last week, she pressed her case directly to the mayor and police chief. She showed up at a news conference in which Lanier and Bowser were discussing arrests in a dozen homicide cases­ in 30 days, an attempt to bring some relief to the District’s rise in deadly violence this year. Krepp interrupted reporters with her own question: Would Bowser support her quest?

The mayor wouldn’t commit to the official request until lawyers read it over. But Bowser told her, “You already have my support in asking the Department of Justice to look very closely at their cases­ and move on their ­cases.”

Bowser said she and Lanier are working with a group of law enforcement officials who meet regularly to find a way to track “cases­ from start to finish — so when there’s an arrest, what’s the charge? When it’s prosecuted, do we get a conviction? When we get a conviction, what’s the sentence? If the sentence is served, is it reduced? When we get people released, do they get proper supervision?”

Lanier has said the public needs to track ­cases. Said Bowser, “We know that will keep communities safer.”