(Deb Lindsey/For The Washington Post)

After a 17-day furor over its decision to strip pork products from the national menu for 206,000 federal inmates, the Bureau of Prisons has finally produced the documentation it says led to the change.

Only it’s different from what the government first said it was.

Late Friday, prison officials provided three years of results from the annual survey of inmates’ food preferences to Sen. Charles E. Grassley (R-Iowa), a senior lawmaker who had asked for an accounting of what he derided as a decision lacking transparency.

[After firestorm, pork roast is back on the menu in federal prisons ]

While prison officials originally said they had banned pork because inmates no longer liked its taste, the survey results show just the opposite: A majority of inmates like pork dishes or have neutral feelings about them, compared to a minority who say they dislike them.

“We re-evaluated the inmate food preference surveys and costs that were considered when the Bureau made the decision to remove pork roast,” Newton E. Kendig, assistant director of the Bureau of Prisons health services division, wrote to Grassley.

[Finally, the government has decided to eliminate pork — from the menu in federal prisons]

“This re-evaluation led us to the conclusion that the decision to remove pork roast was an error.”

Prison officials had pretty much acknowledged that when Director Charles E. Samuels, Jr. ordered pork roast reinstated on the food menu just nine days after its Oct. 1 removal — and the same day Grassley sent Samuels a letter of protest.

But the Bureau of Prisons had unwittingly set off a perfect storm in crossing Grassley, who not only is chairman of the Senate committee that oversees the federal prison system but also represents the country’s largest pork-producing state. Even with pork back on the menu, Grassley wanted answers.

“One out of every three pigs in the U.S. lives in Iowa,” the senator said in an interview last week. The ban had infuriated the pork industry, which sought an explanation from top prison brass.

The inmate surveys showed a preference for pork in 2013, 2014 and 2015, with about two-thirds of those responding indicating that they like or are neutral on pork roast (in 2013, inmates voted on pork roast, pork chops and pork barbeque before the last two dishes were taken off the menu).

Explaining the decision to scrap pork, prison bureau spokesman Edmond Ross originally said that survey results over several years have revealed pork products to be the top disliked items on the inmate menu.

“Additionally, purchase of quality pork products has posed a continued challenge and is often cost prohibitive,” he said.

Explaining the reversal last week, Ross said in an e-mail that inmate food preferences “were one of several factors that were considered for the ban. Other factors include safety and security, the health and welfare of the inmate population, and the cost of our overall operations.”

He declined to elaborate on how inmates’ safety and security was connected to pork.

On Friday, Ross said that concerns about the decision prompted Samuels to tell the food services staff to look at the survey data again.

“We realized it was not properly analyzed,” Ross said. “Looking at the data again, it doesn’t show what we were told it showed.”

The Bureau of Prisons spent $2,975,685 on pork products in the last fiscal year.

Grassley said the pork episode, compared to other investigations his committee undertakes that can last years, got the fastest results he can remember in his long career representing Iowa in the Senate.

“It’s probably the fastest response to any oversight issue I’ve ever worked on,” he said.

“My theory is just like everything else in Washington: It’s an island surrounded by reality, and they weren’t using common sense,” Grassley said of prison officials. “Of course they aren’t going to admit that.”