An Army reservist accused of sexually humiliating inmates at Abu Ghraib prison will plead guilty to charges of abuse, according to a statement his attorney released Monday. Staff Sgt. Ivan L. Frederick would be the second of seven American soldiers charged in the mistreatment scandal to enter that plea.

"I have accepted responsibility for my actions at Abu Ghraib prison," he said in the signed statement. "I will be pleading guilty to certain charges because I have concluded that what I did was a violation of law."

He expressed hope that other Army personnel "who contributed to or participated in the chaos that was Abu Ghraib will also come forward and accept responsibility." The statement was issued a day before Frederick is scheduled to appear at a pre-trial hearing at a U.S. military court in this southern German town.

At hearings here on Monday for two other accused soldiers, the presiding judge expressed frustration with delays by the Army in providing information to the defense and ordered the prosecution to re-investigate and refile charges against one of them.

Revelations of abuse at the prison west of Baghdad touched off expressions of outrage around the world, at a time when the Bush administration was trying to establish a moral high ground for its occupation of Iraq. According to soldiers there, it also increased antipathy toward U.S. forces.

Later this week, two major U.S. government reports concerning Abu Ghraib are due for release. One, commissioned by Defense Secretary Donald H. Rumsfeld, concerns U.S. authorities' overall response to the scandal. The second, from the Army, examines what role military intelligence units played in bringing about abuse.

The defense teams for Frederick and other charged members of the 372nd Military Police Company have argued that senior officers ordered the mistreatment. It was not the work of renegade, undisciplined guards, they maintain, but part of a strategy to extract intelligence from captured Iraqi rebels at a time of mounting U.S. casualties.

Investigators allege that Frederick, who was in charge of the military police who worked the night shift at the prison, forced naked detainees to form a pyramid and to simulate sexual acts. He is also alleged to have been involved in forcing a prisoner to stand on a box with wires placed on his hands. Shown in a widely publicized photograph, the inmate was falsely told he would be electrocuted if he fell off, the military contends.

In an interview, Gary Meyers, Frederick's civilian attorney, said: "We are making prudent choices," with the hope of mitigating Frederick's potential sentence. The statement made no mention of a plea bargain, and did not say which charges Frederick would acknowledge.

In his statement, Frederick expressed concern for the safety of Spec. Joseph Darby, the soldier who helped expose the abuses at the prison by turning over photographs taken there last November. Last week, Darby was placed under protective custody because of threats to his life, news reports said.

"To all who have supported me, I want you to know that I have no bad feelings towards Specialist Darby and neither should you," Frederick said. "He did what he thought was right, and it was right. I ask you to accept that and move on."

In May, Spec. Jeremy C. Sivits pled guilty to four criminal counts in connection with actions at Abu Ghraib and was sentenced to a year in prison. Proceedings have continued against six other soldiers.

Frederick will appear Tuesday before military judge James L. Pohl, an Army colonel who is also overseeing hearings for Spec. Charles Graner, Spec. Megan Ambuhl and Staff Sgt. Javal Davis.

Graner is shown in several abuse photos, including one in which he smiles at the camera from behind a pyramid of naked prisoners. Investigators contend his acts included jumping on piles of prisoners, punching, and stamping on hands and feet; he faces charges that include assault, conspiracy and adultery.

Ambuhl is accused of being present during abuse. The charges she faces include cruelty and ill treatment and indecent acts.

Pohl conducted hearings for both Graner and Ambuhl on Monday and in each case had critical words for the prosecution. U.S. government delays in providing potential evidence for the defense threaten to delay the Graner prosecution, Pohl indicated in court.

The Rumsfeld probe and the military intelligence investigation are behind schedule, as is a third by the Criminal Investigation Command, prosecutors said Monday in offering an explanation for why information had not been turned over to defense attorneys. Graner's civilian attorney, Guy Womack, said he wanted to see testimony from all the probes and get the names and phone numbers for civilian contractors who worked at Abu Ghraib.

Prosecution lawyers offered one illustration of the problems. They told Pohl that as part of the Criminal Investigation Command probe, only one investigator had been tasked with inspecting hundreds of thousands of electronic pages on a secret military Web server in Iraq.

"In what millennium will this be done?" Pohl asked prosecutors. He set an October deadline for information from all the probes. If there appears to be excessive further delay, he warned, he would "seriously revisit" a motion by Womack to dismiss the case against Graner, until all government probes had ended. "The government has to figure out what they want to do with this case," he said.

But not all went well in Monday's hearing for Graner, who wore desert fatigues but not the moustache he sported in photos from Abu Ghraib. Pohl ruled that information and images gleaned from a computer that he used at the prison was admissible as evidence. Graner's attorneys had argued that the computer was improperly inspected after being seized in the MP's Abu Ghraib quarters.

However, Pohl eliminated from future proceedings a statement that Graner made to the initial Army investigator. The defendant told the investigator that everything he was looking for was on the computer. Among the data found were photos of sexual abuse at the prison. Graner had made the statement after saying he wanted a lawyer present during questioning.

Graner's hearing took place in the morning; an afternoon session considered the case of Ambuhl, who also wore fatigues to court.

Pohl told prosecutors they must reinvestigate and refile charges against her. The prosecution had failed to notify her or her defense team of three of the original accusations, the prosecution acknowledged.

The actual trials are scheduled to take place in Baghdad. Womack and other lawyers are pressing for a change in venue to the United States. He said that U.S. civilian witnesses cannot be forced to travel abroad, he told reporters after the hearing.

Monday's hearings were the first time any of the accused had left Baghdad since the scandal broke. Their unit, based in Cresaptown, Md., has returned to the United States.

A courtroom drawing shows Spec. Charles Graner, right, and his attorneys, Guy Womack, center, and Capt. Jay Heath, at the U.S. military court at Taylor Barracks in Mannheim. At left, Womack gives a statement to the media in front of the U.S. military court, where four accused soldiers are facing hearings this week.