Inmates at the Clinton Correctional Facility in upstate New York said the guards who beat them in the days after a brazen escape in June wore no name badges and did not identify themselves.

But one guard, the inmates said, stood out. He had a large tattoo of the American flag down his left arm and was known around the prison as Captain America.

No officer has been publicly implicated in any wrongdoing since an investigation by The New York Times nearly two months ago found what appeared to be a campaign of retribution against dozens of Clinton inmates after the escape at the prison.

Now, through interviews with inmates, The Times has identified Captain America as Chad Stickney, a gang intelligence officer and onetime steward in the state corrections officers’ union.

The inmates’ willingness to come forward and be named speaks to their growing frustration with the pace of the investigation into their allegations. Amid worsening violence at the prison, some inmates said they had been subjected to further harassment after speaking out.

In the frantic days after the prison break, inmates said in letters and interviews with The Times that guards handcuffed them, took them for questioning into areas of the prison with no cameras, punched them and slammed them against the wall. One inmate described having a plastic bag pulled over his head and being threatened with “waterboarding.”

Victor Aponte, 60, who is serving a life sentence for kidnapping and rape, said it was the officer known as Captain America who tied a plastic bag around his neck like a noose during an interrogation and pulled it so tightly that Aponte passed out.

Later, Aponte said, he had asked around at the prison and had learned that the guard was Stickney. Three other prisoners who were at Clinton at the time of the escape, Rashad Scott, Eddie Matos and Luis Zenon, also told The Times that Stickney was Captain America.

Zenon, along with another inmate, Paul Davila, also named a second prison employee, Kevin Norcross, as being present during some beatings. Davila said Norcross had identified himself as a member of the corrections department’s internal affairs unit. While Norcross did not take part in the beatings, the inmates said, he witnessed them.

Inmate accounts are frequently viewed skeptically by investigators. The Times interviewed six inmates at two prisons for this article, and while they gave consistent accounts, their version of events could not be independently verified.

Neither Stickney nor any other officer accused of taking part in beatings after the escape has been criminally charged. James Miller, the spokesman for the corrections officers’ union, said that no officer had been disciplined in connection with the allegations and that Stickney has had a clean disciplinary record in his 18 years as a corrections officer.

Michael Powers, president of the corrections officers’ union, said in a statement that had there been cases of brutality, officers from state, federal and local law enforcement agencies working inside the prison after the escape would have been aware of it.

“It is troubling and irresponsible to report allegations against officers as fact,” Powers said. “Most New Yorkers would question the validity of accusations coming from convicted violent felons, who have long criminal histories and nothing to lose by making such claims.”

Stickney, who was chief steward for the corrections officers union at the Ogdensburg Correctional Facility before moving to the Clinton prison in 2012, has been sued three times for alleged assault and harassment. One of the lawsuits was terminated after the inmate who filed it died. Two others are still active, including a suit filed in September by Terry Daum, an inmate who claimed that Stickney punched him several times in the head and grabbed his genitals during a search. The lawsuit also said “Stickney utilized his hand to aggressively rub plaintiff’s rectum like a credit card swipe and then attempted to jam his fingertips into plaintiff’s rectum.”

Four months after two convicted murderers, Richard W. Matt and David Sweat, escaped through the tunnels under the prison in Dannemora, Clinton remains a tense place. There have been at least three major brawls among inmates, with officers using tear gas and, in one case, live ammunition to bring the prison under control, according to the corrections department.

The state’s inspector general is expected in the coming months to release a report detailing security lapses that led to the escape. And the state Department of Corrections and Community Supervision has promised to investigate inmates’ claims of abuse.

Asked at a recent news conference whether there was a problem with brutality by guards in the state prison system, Gov. Andrew M. Cuomo said that while there may be a few isolated incidents, officers were doing a “good job.”

“State prisons are filled with very dangerous people,” Cuomo, a Democrat, said. “They are policed by a relatively small number of correction officials, who are unarmed, I might add. It is a very, very difficult job. They have to make sure they get a certain amount of respect in the job, otherwise they get hurt.”

The Correctional Association of New York, an inmate advocacy group with a legislative mandate to monitor the prisons, recently interviewed 30 Clinton inmates who described continuing abuse. Of those, two said they had been assaulted by Stickney before the escape; one of the two claimed a plastic bag had been placed over his head during an interrogation.

Stickney did not respond to repeated requests for comment, nor did Norcross.

After complaining about the beatings to investigators, lawyers and reporters, the inmates appear to have suffered further consequences.

Aponte, who described being choked by Stickney, said in a prison interview in September that after the publication of the article in The Times, he was visited by a state corrections department investigator who sought more information. Aponte said he told the investigator who Captain America was.

The status of that investigation is unclear. But Aponte said that after speaking with the Times he was locked in his cell for 23 hours a day and not told why. Patrick Alexander, another inmate who spoke with The Times, was given a disciplinary infraction he believes was fabricated and confined to his cell.

After speaking with investigators, Aponte wrote a letter to the authorities requesting a transfer to another prison because he feared for his safety. He received no response for more than a month. “I’m afraid of retaliation,” he said in an interview in September. “I know how they operate.”

After The Times inquired about Aponte’s request, corrections officials transferred him this week.

The prison break in early June set off a nationwide manhunt. Matt was killed by a federal agent three weeks later; two days after that, Sweat was captured.

The escape highlighted serious security failings at Clinton. Investigators say officers would routinely sleep during overnight shifts, allowing Matt and Sweat to spend hours each night searching the prison’s underground tunnels for a way out.

Joyce E. Mitchell, a former civilian employee at Clinton, was sentenced this week to a minimum of two years and four months in prison after pleading guilty to providing Matt and Sweat with hacksaws and other tools. A guard at the prison has also been criminally charged. Nine officers were suspended after the escape and the prison’s leadership team, including the superintendent, was removed.

No inmates have been charged in the breakout.

In a memo dated Sept. 16, the corrections department warned officers not to punish inmates who spoke to the news media. “An inmate who has been interviewed by representatives of the news media shall not be subject to departmental discipline or any other adverse action,” the memo said.

Alexander said that was exactly what happened to him after he told The Times that officers had beaten him and threatened to use waterboarding during an interrogation shortly after the escape.

At Shawangunk Correctional Facility, where he was transferred, Alexander said he had been verbally harassed by officers who referred to him as the “Clinton inmate” and called him a snitch.

He has also been subjected to frequent frisking by guards, he said, and kept his boots untied so that they could be removed quickly during searches.

In a September interview, Alexander said he had not been compensated for personal possessions lost during his transfer from Clinton, including photo albums, journals, a hot plate, a lamp, beard trimmers and a 13-inch color television.

On Aug. 25, Alexander said that within a few hours of signing a consent form to be interviewed by CNN, he had been singled out by guards to provide a urine sample. Though he had never had a drug infraction during his 11 years in prison, or any other serious disciplinary issue, according to his records, an officer said he was suspected of using marijuana.

A week later, according to prison records, the test came back positive for THC, the psychoactive compound in marijuana.

The corrections department uses a drug test called EMIT that some medical professionals say can yield a false positive for THC. The results from the test given to Alexander should have been verified using a second method, said Dr. Louis Baxter, director of the American Board of Addiction Medicine. The Times provided Baxter with a copy of Alexander’s urinalysis records. “This test I reviewed could have been positive because of the use of ibuprofen,” he wrote in an email.

The corrections department said in a statement that the drug-testing method had been challenged in court and found reliable. Alexander, the statement said, was one of four inmates chosen to be tested as part of an investigation into drug use at Shawangunk.

At a prison hearing, Alexander insisted he had not used marijuana and accused officers of falsifying the test results to punish him for speaking to the media.

The hearing officer found him guilty, confined him to his cell for 30 days and stripped him of privileges, including using the phone and the commissary, for 90 days.

The officer also wanted the television removed from his cell, but Alexander said that would not be necessary because the corrections department had lost it.