(CNN) -- The Minerals Management Service, a division within the Interior Department, was a troubled agency long before the oil spill in the Gulf of Mexico and the recent revelations of employee misconduct.





The agency -- which oversees U.S. offshore drilling, including the Gulf of Mexico -- has come under fire for mismanagement, questionable conduct and cozy relationships with industry officials.





The MMS issued permits for the Deepwater Horizon drill rig -- contracted by BP -- which exploded on April 20. The explosion killed 11 people and resulted in an oil spill that is threatening parts of the Gulf.





Interior Department Secretary Ken Salazar, during an appearance Wednesday before the House Committee on Natural Resources, said he was trying to change the agency's culture and its structure, which some critics say leads to mismanagement.





"My belief is that most of the employees of the MMS are good public servants," Salazar said. He, however, acknowledged some of the past conduct was "scandalous" and "reprehensible."





Salazar said some people have been fired and others referred for prosecution.





Two sources told CNN on Thursday that MMS Director Elizabeth Birnbaum has been fired.





At a House subcommittee hearing Thursday, Salazar insisted Birnbaum had resigned "on her own terms and own volition." President Obama later said he didn't know whether Birnbaum was fired or resigned on her own.





The Obama administration has said in recent weeks that many of the problems within the MMS were inherited from the Bush administration. Salazar, during his testimony and in his answers to members of Congress on Wednesday, also made that point.





During the hearing, Rep. Doug Lamborn, R-Colorado, asked Salazar why he and other officials were "harping on what MMS did or didn't do in the previous administration."





"Why aren't we talking about the here and now?" Lamborn asked.





Salazar was blunt in his response. "We've done a lot to clean the house at MMS, unlike the previous administration," he said. "This is not the candy store of the oil and gas kingdom which you and others were a part of."





Conflict of interest?





The MMS, which has about 1,700 employees, has two responsibilities when it comes to industries such as oil or natural gas. It must act as a regulator while also collecting royalties from the companies.





Some critics say those are opposite pulls and make the agency ripe for mismanagement.





The U.S. government technically owns resources such as the oil in the Gulf. Companies pay the federal government for the rights to drill in certain areas. The MMS collects and distributes about $13 billion a year, Salazar said.





William Galston of the Brookings Institution said there is a built-in conflict of interest, resulting in lax regulation of involved companies.





"The MMS has a lot of incentive to collect as much, in the way of royalty income, as it can. That means pressure to authorize a lot of drilling and then to do everything possible [to make sure] that the flow of production is robust and unimpeded," said Galston, who recently wrote a piece critical of the MMS for The New Republic magazine.





"MMS, as it is currently structured, has to simultaneously put one foot down hard on the gas pedal and the other on the brake," he said. "And the imperatives to go fast are a lot stronger than to slow down."





Salazar said organizational change within the MMS and a restructuring of the agency was necessary to deal with such conflicts.





Salazar advocated plans to "remove revenue collectors away from the leasing and policing functions of the MMS."





He then wants to create two bureaus within the MMS. One would be responsible for creating energy resources -- including oil and gas -- in the outer continental shelf. It would issue leases and collect royalties.





The other would act as the policing arm of the agency, carrying out inspections and enforcing regulations.





'Misconduct, management and spills'





"MMS used to stand for Minerals Management Service. It now stands for misconduct, management and
Who has been fired? Which business has a troubled history? Who has a troubled history? Who is in charge of the Interior Department? Who was fired? What does Ken Salazar say he is attempting to do? Whats the Interior Department chief called?
MMS Director Elizabeth Birnbaum Minerals Management Service, Minerals Management Service, Ken Salazar, MMS Director Elizabeth Birnbaum trying to change the agency's culture and its structure, Secretary Ken Salazar,
question: Who has been fired?, answer: MMS Director Elizabeth Birnbaum | question: Which business has a troubled history?, answer: Minerals Management Service, | question: Who has a troubled history?, answer: Minerals Management Service, | question: Who is in charge of the Interior Department?, answer: Ken Salazar, | question: Who was fired?, answer: MMS Director Elizabeth Birnbaum | question: What does Ken Salazar say he is attempting to do?, answer: trying to change the agency's culture and its structure, | question: Whats the Interior Department chief called?, answer: Secretary Ken Salazar,