Zimbabwe's decision not to prosecute Walter Palmer ends the hopes of protesters that the big-game hunter would be extradited for killing Cecil the lion.

But they have vowed to continue picketing Palmer's Bloomington dental office in their effort to stamp out the sport worldwide.

"He may have gotten away with it, but at least he's going to be the poster boy of trophy hunting," said Catherine Pierce, an East Bethel retiree moved to action by Cecil's death. "It's not the end of the road."

Zimbabwe's Environment Minister Oppah Muchinguri-Kashiri told reporters there Monday that Palmer's papers to hunt "were in order."

"The documents were there," she said. "We are now going to review how we issue hunting quotas."

Muchinguri-Kashiri said that Palmer can now safely return to Zimbabwe as a "tourist" to the southern African country, but not for hunting.

Walter Palmer has said he had no idea that the lion killed was a prized research animal.

A spokesman for Palmer in the Twin Cities said Monday that he would have nothing to say about the decision.

Legal professionals had raised doubts whether an extradition of Palmer would occur for a suspected wildlife crime. Officials of the U.S. Fish and Wildlife Service (USFWS) said weeks ago that they were investigating Cecil's killing and assisting Zimbabwe in its case. USFWS spokesman Gavin Shire said Tuesday that his agency continues to investigate Palmer's killing of the lion. Shire declined to reveal anything further about the probe.

A Justice Department spokesman accepted a series of questions about Palmer's case early Monday afternoon but had yet to respond.

The minister's decision, coming after earlier promises to prosecute Palmer and seek extradition, caught members of Zimbabwe's safari hunting industry off-guard.

"It is surprising because we have that important agenda to have our wildlife protected and that any bad behavior, whether it is by the operator or the visitor, is punished accordingly," said Emmanuel Fundira, president of the Safari Operators Association of Zimbabwe.

Fundira said the decision also weakens the case against Palmer's professional hunting guide, Theo Bronkhorst, and landowner Honest Trymore Ndlovu, on whose land Palmer shot the lion. Charges were filed against both of those men and their cases are pending.

Bronkhorst's lawyer, Givemore Mvhiringi, said he read about the decision on the Internet.

"If it is true, then the Honourable Minister's latest position dovetails with our position that Mr. Palmer and indeed our client Mr. Theo Bronkhorst had committed no offense," he told the Star Tribune by e-mail.

Ingrid Newkirk, president of People for the Ethical Treatment of Animals, said that while others "will bear [legal] responsibility for Cecil's slaughter … we're encouraged that Walter Palmer lost business, lost his reputation, and probably lost more in the bargain — while Cecil's death sent a strong message to wildlife slayers that their days are numbered."

Palmer, 55, who lives in Eden Prairie, had been away from his practice and out of public view since late July, when a London newspaper revealed that he had killed the lion with a bow and arrow in what Zimbabwe authorities had alleged was an illegal hunt earlier in the summer.

A marksman and accomplished big-game hunter, Palmer reportedly paid about $50,000 for the guided hunt outside of Hwange National Park. Authorities in Zimbabwe allege that the 13-year-old lion with the distinctive black mane was lured from the national park onto a neighboring farm.

Palmer's dental office became a focal point for angry protests, and he suspended his practice amid the commotion. Critics also took to social media with a fury. Some condemned trophy hunting, while others tapped out threats against Palmer and his family. The heated online entries forced the practice to shut down its social media and business Web pages.

Palmer has always maintained that the hunt was legal, and that he had no idea the lion he felled was a long-studied and well-known animal.

Anna Frostic, senior attorney for wildlife litigation at the Humane Society of the United States, said she doesn't expect to see Palmer prosecuted in the United States "unless additional facts come to light that change the status quo."

Correspondent Thulani Mpofu in Zimbabwe contributed to this report.