Federal investigators on Wednesday said they will move ahead with a planned autopsy of the blowout preventer that failed to stop gushing oil at BP's Macondo well, even if the U.S. Chemical Safety Board isn't happy with the plan. The joint investigation by the Coast Guard and Interior Department has already postponed its final conclusions on the Deepwater Horizon disaster by two months and officials said any further delay in examining the massive BOP risks further delays. 'It is imperative that the investigation into the BP oil spill continue in a timely fashion in order to hold the responsible parties fully accountable for this unprecedented disaster,' said Eileen Angelico, a spokesperson for the joint investigation by the Coast Guard and the Interior Department's Bureau of Ocean Energy Management, Regulation and Enforcement. 'The (joint investigation team) has been open and transparent to interagency partners and the public. This has included cooperating with the Chemical Safety Board to accommodate (its) needs.' The 300-ton blowout preventer -- which was retrieved from the seafloor after oil stopped flowing into the Gulf and is now stored at a NASA facility in Louisiana -- was designed as a last line of defense against an unexpected surge of natural gas or oil. The conflict between the chemical board and JIT centers on who will be inside the testing facility whenever a government-contracted Norwegian firm runs it through tests that could determine why it failed in its mission of stopping out-of-control oil and gas flowing from BP's well. The presidentially appointed chemical board has demanded more access to the testing room and documentation of the examination. The clash also involves more fundamental questions about the independence of the testing and how it should be conducted, as well as the role of the agencies investigating the disaster. The JIT, which is managing the testing, has given the board one of six coveted seats in the room for the tests, alongside representatives from BP; rig owner Transocean; the BOP manufacturer, Cameron International; the Justice Department and the plaintiffs in a lawsuit against BP. JIT leaders envision that the six seats will be filled by a 'technical working group' of experts who can advise the Norwegian firm Det Norske Veritas at critical points in the examination. The JIT had planned to vet and approve the seat-fillers. But the 20-year-old board -- an independent federal agency that has probed dozens of industrial accidents -- insists that it should be allowed to periodically send in one of its own investigators to coordinate with any contracted expert it already has in the room. Board leaders chafe at the notion of getting prior approval for their experts and contend that this would threaten the independence of the agency and its probe of the Deepwater Horizon disaster, which was requested by the House Energy and Commerce Committee. The board also has asked for high-resolution photos from the examination every day. The requests have added weight because some testing of the BOP can only be done accurately once, said Donald Holmstrom, the board investigator-in-charge. 'If we're not there and able to capture all the information we can, then we're not going to be in a position to conduct this investigation,' Holmstrom said. 'We see this as sort of the tip of the iceberg. If we can't participate efficiently in the testing of the BOP,' then what happens with any additional testing of other equipment down the road? The issue of the board's autonomy also could loom large if the agency pursues interviews with federal regulators at the Interior Department, which played a critical role in approving work on the Macondo project. Board officials have said they hoped a compromise will be reached, but were cool to a proposed agreement submitted by the JIT on Tuesday. Although space inside the testing facility is limited, video of the forensic testing will be streamed to others on the site. The JIT initially had decided to allow five experts in the room, before adding one more space to accommodate the board. Still there are disputes about the board's authority. Although the House Energy and Commerce Committee asked the board to investigate the oil spill, a federal statute says the board it is not authorized to conduct investigations of 'marine oil spills.' The interpretation of that is not clear. (Jennifer A. Dlouhy can be reached at 202-263-6400 or at the e-mail address jdlouhy(a)hearstdc.com) 