For several months, a few dozen men being held without bail in connection with the Jan. 6 attack on the Capitol have loudly and repeatedly complained about conditions at the District of Columbia jail.

Some, through their lawyers, have raised concerns about threats from guards, standing sewage, and scant food and water. A federal judge recently held top jail officials in contempt after they delayed prompt medical care for a Capitol defendant in their custody. Just last week, Representative Marjorie Taylor Greene, Republican of Georgia, visited the jail and later likened the rioters inside to “prisoners of war,” suggesting that they had been mistreated because of their politics.

None of these allegations of neglect came as a surprise to local Washington officials, many of whom have complained about conditions at the jail for years. Still, at a public hearing this week, some expressed frustration that, despite longstanding problems at the jail, it took the arrival of a small group of out-of-town — and largely white — defendants to finally get anyone to care.

“Recent reports about squalid conditions in the district jails are unfortunately not new,” Karl A. Racine, Washington’s attorney general, said at the hearing. Mr. Racine went on to say that “concerns about conditions at the jail received little attention until they were raised by mostly white defendants accused of perpetrating the Jan. 6 insurrection.”

While the 40 or so Capitol rioters housed at the jail are only a fraction of the roughly 1,400 inmates being held there altogether, their complaints about the place — which began almost immediately — have received outsize publicity.

In court papers, several have asserted that they have been denied the right to conduct religious services and that their basic hygiene needs have not been met. At public hearings related to their cases, others have protested about roaches in their cells or the length of their detention.

In September, as complaints about the jail increased in volume, a onetime campaign aide for former President Donald J. Trump held a rally in Washington in support of the defendants, billing the event as “Justice for J6.” But even though many on the right routinely refer to the rioters in custody as “political prisoners” (and to the section of the jail where they are kept as “the patriot wing”), few people — and almost no top Republican officials — attended the gathering in their honor.

What set off this latest round of protest was an episode involving Christopher Worrell, a member of the far-right group the Proud Boys, who has been at the jail since his arrest this spring. Mr. Worrell, who has cancer, broke one of his pinkies while in custody (though initial reports said it was his wrist). After several failed attempts to get him treatment for the finger, his lawyer asked a federal judge for help.

The judge, Royce C. Lamberth, tried to get officials at the jail to accelerate the process of providing medical records to Mr. Worrell’s lawyer and after a number of delays, he angrily held the officials in contempt. As part of his contempt decision, Judge Lamberth recommended that the Justice Department investigate conditions at the jail to determine whether the civil rights of any other Jan. 6 defendants had been violated.

Within days, the U.S. Marshals Service, which oversees federal detainees, opened an inquiry into the jail and soon determined, among other things, that there were sewage and water leaks inside and that corrections officers often antagonized their charges, sometimes withholding food and water for “punitive reasons.”

The most serious problems, the marshals found, were in an older part of the jail complex called the Central Detention Facility, not in the Correctional Treatment Facility, where all of the Jan. 6 defendants are held.

After a report by the marshals was released, complaints by the riot inmates, if anything, got louder. In late October, a “cry for help” by one of the defendants, Nathan DeGrave, was released on Twitter. It referred to the D.C. jail as “Gitmo” and accused jail officials of subjecting the “Jan 6ers” to “psychological and mental abuse.”

One week later, Ms. Greene went to the jail and met with the defendants, later noting that they gather every night before retiring to bed to sing the national anthem. After her inspection, Ms. Greene appeared on a podcast hosted by the former Trump adviser Stephen K. Bannon and declared that conditions in the jail were far worse than those facing homeless people or terrorists.

Amid these expressions of outrage, it was never mentioned that the jail had been plagued with problems long before the Jan. 6 defendants got there. Six years ago, for instance, the Washington Lawyers’ Committee for Civil Rights and Urban Affairs issued a report calling the conditions at the jail “appalling.” The troubles have been so persistent that this year, a local task force released a plan to close the facility and replace it with a new one.

Activists in Washington who have dedicated years to solving problems at the jail seemed grateful, in a sense, that the issue was finally getting the attention it deserved. But some expressed concern that officials who appeared at the public hearing, which took place on Wednesday, were feigning ignorance about the longstanding predicament.

Patrice Sulton, the executive director of the DC Justice Lab, an organization that advocates criminal justice reform, said she was particularly frustrated that it took complaints from the recently arrived Jan. 6 defendants, most of whom are white, to get the authorities to focus on the plight of detainees at the jail, almost all of whom are Black.

“It just doesn’t sit well,” Ms. Sulton said.