Updated at 6:22 p.m. EST.

A GOP investigator in the House is questioning Obama administration officials about scientific decisions made during last summer's response to the Gulf of Mexico oil spill.

House Science and Technology Investigations and Oversight Chairman Paul Broun (R-Ga.) yesterday sent letters to President Obama, National Oceanic and Atmospheric Administration Administrator Jane Lubchenco and White House energy adviser Carol Browner, questioning the administration's decisionmaking process during the response.

"I have sought answers to these questions for months and have been stonewalled in my efforts to shed light on how science was used, or misused, to make decisions relating to this national tragedy," Broun said in a statement. "Time and time again, press reports and independent investigations have highlighted instances where science was ignored or muzzled, peer review was mischaracterized and spin control trumped transparency."

Specifically, Broun is concerned about the administration's development of a document that accounted for the fate of the oil, its estimation of the amount of oil flowing into the Gulf and its release of a document calling for a moratorium on deepwater drilling.

The so-called oil budget that Broun references in his letter to Obama has come under heavy criticism in the months since it was released. The document, which accounted for the spilled oil, indicating the amounts that had been burned, skimmed and dispersed, claimed that all but 26 percent of the oil could be accounted for at the time of its release in early August 2010. And lawmakers, academics and environmentalists criticized the Obama administration for using the document to paint an optimistic picture of the situation in the Gulf.

The findings of the report were later backed by an independently peer-reviewed final draft released in November, but questions still remain about the preparation of the original document (E&ENews PM. Jan. 25).

In his letter to Browner, Broun questions the decisionmaking process involved in preparing an Interior Department report released in May that called for the federal moratorium on deepwater drilling. Interior's Inspector General found last fall that the White House tampered with language in the report, implying that a group of independent scientists supported language recommending the ban.

"While the [inspector general's report] goes to great lengths to identify the apologies made by DOI Secretary Ken Salazar to the scientists in writing as well as through phone conversations, it is notably silent on the role played by your office," Broun wrote. "There is no evidence of acknowledgement by you or your staff for the changes they made that led to the misrepresentation -- changes that were sent in the middle of the night, just hours before the report's release."

In his letter to Lubchenco, Broun questioned decisions made by the administration while it struggled to determine an accurate flow rate estimate.

The issues addressed in Broun's letters have been raised numerous times in the months since the Deepwater Horizon drilling rig exploded last April. But the administration has defended its response to the spill, and in cases like the oil budget, the administration's findings have been backed by independent scientists.

Click here to read Broun's letter to Obama.

Click here to read Broun's letter to Browner.

Click here to read Broun's letter to Lubchenco.