WASHINGTON (AP) -- Intelligence experts were worried three years ago about the possible theft of secrets about America's nuclear arsenal and believed the Los Alamos weapons lab was the most likely source, an Energy Department intelligence officer told a Senate panel Thursday. Earlier this year, investigators found the missing ``legacy'' codes, which contain years of cumulative data about the nation's nuclear warheads, in the unsecure computer of a Los Alamos, N.M., scientist suspected of espionage. ``What was done, in short, was nothing,'' Notra Trulock, acting deputy director of the Energy Department's Office of Intelligence, said of the concerns expressed by intelligence experts in early 1996 about potential loss of the top-secret computer codes. Lawmakers have applauded Trulock for raising alarms as early as 1995 about the possible theft of nuclear secrets from weapons labs, including information in the 1980s about a sophisticated warhead known as the W-88. That theft has been the subject of a four-year espionage investigation that prompted the firing of the Los Alamos scientist in March. The scientist, Wen Ho Lee, has not been charged with a crime and has denied giving secrets to China or anyone else. Energy Secretary Bill Richardson, appearing elsewhere on Capitol Hill, said the file transfers at Los Alamos, discovered in March, were ``an incredible breach of security'' but that with new computer safeguards ``that cannot happen again.'' ``It's now impossible to download material from the classified computers,'' Richardson assured the House Science Committee. Trulock, appearing before the Senate Energy and Natural Resources Committee, described repeated attempts in early 1997 to bring his concerns about espionage and lax security at weapons labs to then-Energy Secretary Federico Pena. He said he was repeatedly thwarted by senior DOE officials, including Pena's deputy, Elizabeth Moler, and that Pena knew nothing of the espionage concerns for about six months. Trulock in the past also has accused Moler of muzzling him when he tried to testify before Congress. Moler has denied she tried to block Trulock. The allegations have been investigated by the DOE's inspector general, but the report has not yet been released. An internal investigation into the handling of the Los Alamos espionage case is near completion and is expected to result in disciplinary action against some DOE and laboratory officials and possibly former officials. ``Why heads are not rolling is beyond me,'' declared Sen. Conrad Burns, R-Mont. Trulock, who was director of the Office of Intelligence from 1994 into early 1998, said his concerns about espionage at the labs were viewed in 1997 with skepticism and ``outright denial'' among senior DOE officials. They were dismissed as views of ``Cold War warriors,'' said Trulock. He said the investigation at Los Alamos into apparent loss of secrets about the W-88 warhead was viewed as ``merely a historical curiosity and of little relevance.'' Ed Curran, the FBI official appointed a year ago to consolidate and lead counterintelligence efforts at the department, acknowledged that in the past there had been ``no accountability'' and inadequate support from top officials of the department on intelligence and security matters. Sen. Frank Murkowski, R-Alaska, the committee chairman, derided the ``cavalier attitude about security'' described by Trulock and suggested that senior administration officials should not be let off the hook. Richardson acknowledged that ``security was given second fiddle'' at the department, but he declined to criticize his predecessors. ``I'm not going to get into the blame game,'' he told reporters. Meanwhile, a 700-page report by a special House committee examining U.S. technology losses to China will conclude that China has been able to make substantial gains in modernizing its nuclear weapons program because of U.S. secrets obtained in a pervasive campaign of espionage and misuse of legally obtained technology. Senate Majority Leader Trent Lott, R-Miss., said after being briefed behind closed doors on the House report that ``you almost have to measure in megatons'' the security damage from Chinese espionage. He provided no details. The report, a year in the making, is to be released early next week, after months of wrangling between lawmakers and the Clinton administration over how much of it should be kept secret. According to officials familiar with it, the report concludes that there is little question that China has obtained critical information about an array of U.S. warheads through theft from U.S. nuclear weapons labs as well as meticulous scanning of publicly available information. Many details of the report have been leaked in recent weeks. Amid a string of embarrassing revelations in the news media about suspected Chinese espionage and lax security at the labs, Richardson has revamped the department security structure, imposed tighter controls on computers at the labs and directed other new security measures. Attorney General Janet Reno announced on Thursday that a veteran prosecutor, Randy Bellows, would head a Justice Department investigation into whether Justice or the FBI made any mistakes in the Wen Ho Lee investigation dating to 1982, when his name first surfaced. -=-=- 