Washington ? Called before Congress to account for the sordid abuses at Iraq’s Abu Ghraib prison, Defense Secretary Donald Rumsfeld struck an unaccustomed attitude Friday: chastened and humble.

Rumsfeld took some of the blame: “These events occurred on my watch. As secretary of defense, I am accountable for them and I take full responsibility.”

He offered his “deepest apology” — and compensation — to the abused Iraqis: “I feel terrible about what happened to these Iraqi detainees. They’re human beings.”

He also apologized to Congress, President Bush, the armed forces and the American people. Rumsfeld even admitted he had thought about resigning.

And he warned that the scandal might deepen. “Be on notice,” he said. “There are a lot more photographs and videos that exist. If these are released to the public, obviously it’s going to make matters worse.”

But as his daylong appearances before the Senate Armed Services Committee and its House counterpart unfolded, the more familiar Donald Rumsfeld — blunt and combative — returned.

Backed by Bush’s declaration Thursday that Rumsfeld would “stay in my Cabinet,” the defense secretary rejected Democrats’ demands for his resignation.

He disputed accusations that the Pentagon tried to suppress the Abu Ghraib story, which broke into the spotlight last week when CBS broadcast images of American soldiers smiling next to nude or nearly-nude Iraqi prisoners.

Rumsfeld told lawmakers it might have interfered with prosecutions had he inquired too soon and too deeply into an investigation that was announced in January.

And he emphasized that “there are 18,000 criminal investigations opened a year in the Department of Defense,” about 3,000 of which lead to courts-martial. There was “no way in the world I could anticipate” the gravity of a particular investigation, he said.

“He was quite contrite; there were times when he was quite feisty,” said Sen. Joe Lieberman, D-Conn.

Bipartisan questioning

Democrats and Republicans alike asked Rumsfeld pointed questions about a scandal that John Warner, R-Va., chairman of the Senate panel, said constituted “as serious an issue of military misconduct as I have ever observed.”

Sen. Carl Levin, D-Mich., chastised Rumsfeld and Air Force Gen. Richard Myers, chairman of the Joint Chiefs of Staff, for failing to tell lawmakers in a closed briefing last week that CBS’s “60 Minutes II” would air shocking photos of the abuses that very evening.

Sen. Robert Byrd, D-W.Va., a bitter foe of Bush’s decision to invade Iraq, chided: “I do not recall hearing a peep out of either of you, Secretary Rumsfeld, or General Myers, about this before CBS broke the silence.”

“Senator, the facts are somewhat different than that,” Rumsfeld retorted. “The story was broken by the Central Command by the United States Department of Defense in Baghdad.”

He was referring to a Jan. 16 news release that said in part: “An investigation has been initiated into reported incidents of detainee abuse at a Coalition Forces detention facility. The release of specific information concerning the incidents could hinder the investigation.”

But Sen. Susan Collins, R-Maine, said she was “troubled by the Pentagon’s failure to come forward” about the abuses.

“I’m not talking about issuing a press release from Baghdad,” she said. “I’m talking about you personally coming forward and telling the world what you knew about this abuse.”

Sen. Lindsey Graham, R-S.C., a former military prosecutor, told Rumsfeld he would be “very disappointed if the only people prosecuted are sergeants and privates.”

Rumsfeld said the “pictures I’ve seen depict conduct, behavior, that is so brutal and so cruel and so inhumane that anyone engaged in it or involved in it would have to be brought to justice.”

‘Radioactive’ scandal

Flanked by Myers, two other generals, acting Army Secretary Les Brownlee and about 40 military and civilian aides, Rumsfeld appeared at hearings that were as much about him as about the military police accused of using sexual degradation to “soften up” Iraqi prisoners for questioning by intelligence interrogators.

After the morning hearing, in which Graham asked if he thought he could “still be effective” as defense secretary, the senator told reporters: “I thought he did a good job saying ‘I’m sorry.’ I’m still unclear about who knew what when, and that’s important, in terms of how much accountability to assess to someone.”

As Rumsfeld delivered his opening statement to the Senate panel, he was interrupted by a half dozen protesters who stood in the audience and began shouting, “Fire Rumsfeld for war crimes!” They were escorted from the standing-room-only hearing room without incident.

Rumsfeld told lawmakers that neither he nor others at the top of the Pentagon had appreciated how “radioactive” the scandal would be because the photos were unknown to them until they learned CBS had them.

But Sen. Hillary Clinton, D-N.Y., countered that the “atrocities” were well-described in a report by an Army general.

“It doesn’t take a lot of imagination to read those descriptions and have one’s stomach just turn in disgust,” she said. “The focus on the pictures being released is, with all due respect, missing the point.”

Further examination

Rumsfeld also emphasized that the Army responded swiftly when allegations of abuse were brought to commanders Jan. 13 by a soldier, and that the Army and Pentagon have initiated six investigations of detainee handling in Iraq and elsewhere.

And he said a panel of “senior former officials” would “examine the pace, the breadth, the thoroughness of the existing investigations, and to determine whether additional investigations or studies need to be initiated.”

But Rep. Ike Skelton of Missouri, senior Democrat on the House committee, said that was “not enough.”

“We must hold an independent congressional investigation into these abuses and into the command atmosphere that permitted them to occur,” Skelton declared. “Congress, having not been informed, must now be involved.”