WASHINGTON — Military lawyers warned against the harsh detainee interrogation techniques approved by Defense Secretary Donald Rumsfeld in 2002, contending in separate memos weeks before Rumsfeld's endorsement that they could be illegal, a Senate panel has found.

The investigation by the Senate Armed Services Committee also has confirmed that senior administration officials, including the Pentagon's then-general counsel William "Jim" Haynes, sought information on a program involving military psychologists early on to devise the more aggressive methods — which included the use of dogs, making a detainee stand for long periods of time and forced nudity, according to officials familiar with the findings.

The officials spoke on condition of anonymity because the information has not been formally released. Details, including the names of the service lawyers who objected to the interrogation techniques, were to be discussed at an open committee hearing today. Rumsfeld's December 2002 approval of the aggressive interrogation techniques and later objections by military lawyers have been widely reported. But the November protests by service lawyers had not, and the interest by Pentagon civilians in military psychologists has surfaced only piecemeal.

The lawyers' objections were sent to the Joint Staff, which would have relayed the messages to civilian leadership. There is no proof, however, that Rumsfeld or Haynes personally saw the memos.

Today's hearing is the committee's first look at where the harsher methods — used in Guantanamo Bay prison in Cuba and Abu Ghraib in Iraq — originated and how policy decisions on interrogations were vetted across the Defense Department.

The review fits into a broader picture of the government's handling of detainees, which includes FBI and CIA interrogations in secret prisons.

Ultimately, Democrats say the Senate investigation will prove that abusive conditions in some military prisons were not — as the administration contends — the result of a few "bad apples" but rather the consequence of senior defense civilians anxious to extract intelligence in the months following the Sept. 11 attacks.

"Senior officials in the United States government sought out information on aggressive techniques, twisted the law to create the appearance of their legality and authorized their use against detainees," said Sen. Carl Levin, D-Mich., who will preside over Today's hearing as Armed Services Committee chairman.

The panel is expected to hold further hearings on the matter and release a final report by the end of the year.

Haynes, who resigned in February after nearly seven years as the military's top civilian lawyer, is expected to testify today. He is now chief counsel to the Chevron Corp. in San Ramon, Calif. Also present will be Richard Shiffrin, Haynes' former deputy on intelligence matters, as well as legal advisers at the time to the chairman of the Joint Chiefs of Staff and the Guantanamo Bay prison.

Alberto Mora, former general counsel for the Navy, will be the only service lawyer to testify.

According to the Senate committee's findings, Haynes became interested in using harsher interrogation methods as early as July 2002 when he sent a memo inquiring about a military program that trained Army soldiers how to survive enemy interrogations and deny foes valuable intelligence.

Officials who taught the methods — known as "Survival, Evasion, Resistance and Escape," or SERE techniques — were well schooled in the art of abusive interrogations.

Jerald Ogrisseg, a former top military psychologist, is expected to testify Tuesday that the SERE program was designed for defensive training purposes and was never intended to be reverse-engineered as a means of finding tougher ways to interrogate U.S. prisoners.

Shortly after requesting more information about the use of SERE techniques, Haynes traveled in September 2002 to Guantanamo Bay with other administration lawyers, including then-White House Counsel Alberto Gonzales and Vice President Dick Cheney's chief counsel, David Addington.

A month later, in October the military commander in charge of Guantanamo Bay, Gen. Michael Dunlavey, asked his superiors at U.S. Southern Command for approval to employ harsher interrogations. His request was based in part on a legal review by Air Force Lt. Col. Diane Beaver, a lawyer assigned to the task force running the Cuban prison.

Beaver also is expected to testify Tuesday.

According to officials familiar with the Senate investigation, the proposal prompted protests from the services' uniformed lawyers. Each of the service lawyers told the Joint Staff that the techniques warranted further study, and the Air Force and Army specifically warned that the methods could be illegal.

Their objections were ignored. Several weeks later, in December 2002, Rumsfeld approved more than a dozen interrogation techniques that went beyond those authorized in the Army Field Manual, which is based on Geneva Convention standards for the humane treatment of war prisoners. His approval was based on a recommendation from Haynes.

In a statement provided through his lawyer, Haynes said that dealing with the terrorist threat after Sept. 11 "presented the United States with urgent, unprecedented and complex challenges."

"One of my goals as chief legal officer of the Department of Defense was to support the department's efforts to gather critical intelligence lawfully in order to protect the American people from further terrorist attacks," he said.

Rumsfeld later rescinded his own memo and issued new guidance in April 2003.

Mora was among those military lawyers who logged objections to the administration's treatment of detainees in that 2002 and 2003 timeframe, according to a February 2006 article in The New Yorker. In a July 2004 memo, shortly after images surfaced of abuses at Abu Ghraib, Mora detailed his 2 1/2-year effort to halt a policy that he said was illegal and cruel.