Notra Trulock, the intelligence official who triggered the federal government's investigation into suspected Chinese espionage at Los Alamos National Laboratory, resigned yesterday amid growing controversy about his handling of the case.

Trulock said in an interview he quit because the Department of Energy's inspector general last week issued a report that failed to back him up and hold senior Clinton administration officials accountable for security failures at Los Alamos. He called the report "a whitewash" and said, "I think the time has come for me to move on. I've done all I could do here."

Trulock has come under mounting pressure in recent weeks as two government reports and a growing number of intelligence and security officials sharply criticized him for singling out Wen Ho Lee, a Chinese American physicist at Los Alamos, as the government's prime espionage suspect.

Three officials who participated in various stages of the investigation have said they believe Trulock and FBI agents focused on Lee largely because of his ethnicity. At least three other Energy Department employees have filed grievances against Trulock for alleged discrimination and retaliation on the job.

Trulock's resignation as the department's deputy director of intelligence -- he was demoted last year after serving as director of intelligence for four years -- is the latest twist in a year of charges and countercharges about Chinese nuclear espionage.

At least five high-level government reviews have concluded that China's intelligence service has targeted U.S. weapons laboratories and succeeded over the past two decades in obtaining some information about the design of nuclear weapons, including the W-88, the United States's most advanced warhead. The Central Intelligence Agency, the President's Foreign Intelligence Advisory Board and two congressional inquiries also have concluded that security and counterintelligence at the nation's weapons labs have been lax.

But most of the experts who have looked into the suspected Chinese espionage have concluded that it is not clear exactly how much classified data China has obtained or where the information came from. There is also a continuing debate about the value of the information and whether China has used it to update its nuclear arsenal.

Trulock has been a central figure in the espionage probe and an influential proponent of the view that China stole significant secrets from Los Alamos. When the allegations became public early this year, leading Republicans in Congress accused the Clinton administration of dragging its feet and hailed Trulock as a hero for drawing attention to security lapses at the weapons labs.

In March, Energy Secretary Bill Richardson fired Lee from his job in Los Alamos's top-secret X Division for violating security regulations by transferring classified files to an unclassified computer in his office.

Lee, a Taiwan-born nuclear physicist and U.S. citizen, has denied passing secrets to China and has not been charged with any crime. The Justice Department is considering whether to prosecute him for violating security procedures. But federal officials have acknowledged that they have no evidence that would warrant charging him with espionage.

Appearing on NBC's "Meet The Press" in May, Trulock expressed no reservations about the government's evidence, comparing the possible loss of nuclear secrets at Los Alamos to "the Rosenbergs-Fuchs compromise of the Manhattan Project information" at the end of World War II.

In June, however, the President's Foreign Intelligence Advisory Board criticized Trulock and other investigators for focusing almost exclusively on Lee when there was no solid evidence that he, or anyone else at Los Alamos, was the source of classified information that China had somehow obtained about the W-88.

Even sharper criticism was leveled at Trulock last week by Robert S. Vrooman, the former chief of counterintelligence at Los Alamos, who said Trulock and federal investigators had singled out Lee as the government's prime espionage suspect because he is a Chinese American.

Vrooman said Trulock and FBI agents pushed the case against Lee and ignored numerous "Caucasian" employees at Los Alamos who had similar access to secrets and had made similar trips to scientific conferences in China. "This case was screwed up because there was nothing there -- it was built on thin air," Vrooman said.

Trulock's supporters have suggested that Vrooman may have an ax to grind because he is facing possible disciplinary action for failing to cut off Lee's access to secrets.

In subsequent interviews, two other senior counterintelligence officials with direct knowledge of the Lee case -- one at DOE headquarters, and one at Los Alamos -- have said they believe that Lee was singled out because of his ethnicity.

Charles E. Washington, who was DOE's acting director of counterintelligence in 1996 when Trulock first started pursuing the espionage investigation at Los Alamos, gave The Washington Post a copy of a memorandum he wrote to Trulock at the time recommending that the case be closed for lack of evidence.

Washington said he told Trulock that he was unfairly singling out Lee and another Chinese American scientist at Los Alamos when numerous others had similar access to secrets. And Washington alleged that Trulock was motivated at least in part by a desire to win a larger budget for Energy's relatively small intelligence office, which he headed.

"Trulock used to say, `We need one good espionage case to make this program grow,' " Washington said last week in an interview. "He said, `There's one spy out there, and we're going to find him.' "

Washington, who is African American, is suing the Energy Department in federal court for alleged discrimination and retaliation by Trulock and has been on extended sick leave, undergoing treatment for stress, since January. Washington said his problems with Trulock began shortly after he expressed opposition to proceeding with the case against Lee and questioned Trulock's competence to run a counterintelligence investigation.

Michael S. Soukup, a physicist at Los Alamos who has spent years studying China's nuclear weapons testing and design complex, also said yesterday that he believes that Trulock and the FBI targeted Lee because he is Chinese American.

Soukup said in an e-mail message to The Post that "it became very clear to me that this investigation was driven almost exclusively by Notra Trulock."

Soukup said the "suspicion matrix" developed by investigators "was, and still is, a sham. I fit their matrix perfectly, and I was never interviewed and questioned."

Trulock responded yesterday that "there never was a matrix" and denied that he singled out Lee based on ethnicity.

"I'm sort of at a loss to understand how Vrooman thinks DOE singled out Wen Ho Lee, when there were 12 people on the list" of suspects forwarded to the FBI, Trulock said. "To allege as Vrooman has that ethnic profiling was used in this case is outrageous and false. I categorically deny that. We went to a dozen facilities and looked at a decade's worth of records. I'm satisfied that DOE did its job in this."

Trulock also denied as "ridiculous" and "absolutely false" Washington's assertion that Trulock had talked about making a high-profile espionage case to enhance funding for his office.

Trulock said he had informed his boss, DOE intelligence chief Larry Sanchez, yesterday morning that he would be resigning by the close of business. Trulock said he will begin work this morning at TRW Inc., a high-technology defense contractor with offices in Northern Virginia.

Energy Secretary Richardson was described yesterday as "disappointed" by Trulock's decision to leave the department, according to Brooke Anderson, Energy's spokeswoman.

Richardson said Trulock "performed valuable work" in persistently pursuing and uncovering evidence of espionage, for which he was awarded a $10,000 bonus, Anderson said in a written statement.

But she added that Richardson supported the Energy inspector general's report and rejected Trulock's contention that it was "a whitewash."