The public was outraged by the pictures of fifteen uniformed men standing beside Pepe the Hippo’s body. The most vocal protesters demanded that the Minister of Environment resign. Newspapers ran angry letters from readers, and the outcry soon led a judge to prohibit further hippo killings.

The common hippopotamus is classified as ‘vulnerable’ by the International Union for Conservation of Nature, with the species’ numbers threatened in part by hunting for their meat and ivory teeth. But Pepe was not shot by poachers. His death in June 2009 was sanctioned by environmental authorities–in Colombia.

Hippos are native to Africa, not South America. Pepe was in Colombia as one of nearly 60 wild hippos living around Hacienda Nápoles, a ranch southeast of Medellín. Some of the hippos have already made it to the nearby Magdalena River, with a few sighted more than 150 miles away.

These hippos of Colombia are larger than any other wild animals on the continent and are reproducing faster than their African counterparts. They threaten the local wildlife–and nearby humans. But they would never have been in Colombia if not for the drug lord Pablo Escobar.

From his base in Medellín, Escobar ran a criminal organization that, at its peak in the 1980s, was estimated to have reaped $400 million each week. According to his accountant, Escobar was handling so much cash that he spent $2,500 each month on rubber bands to hold together the bills.

The Medellín Cartel was the main supplier of smuggled cocaine to the United States. Using the strategy of plata o plomo (loosely, money or bullets), it won enormous influence within the country. The cartel bought politicians and the police–when Escobar was eventually captured, he was housed in a luxurious prison with a jacuzzi, from which he later escaped.

But through a campaign of terror, his enemies paid dearly. Escobar was reportedly behind a 1985 siege of the Colombian Supreme Court, the assassination of the frontrunner in the country’s 1990 presidential election, and, as part of a failed attempt to kill that vote’s eventual winner, an airplane bombing that killed 110.

Escobar also accumulated extraordinary personal wealth, with Forbes listing him as a billionaire in each of the last seven years of his life. In 1989, the magazine named him the world’s seventh-richest person, and some estimates placed his net worth at $30 billion. Escobar used his fortune to fund schools and hospitals, winning admiration from many Colombians. But he also funded extravagant projects like his ranch–Hacienda Nápoles–which he kept stocked with elephants, rhinos, ostriches, giraffes, and hippos.

Carlos Valderrama, a veterinarian with the charity Webconserva who has worked with the descendants of Escobar’s hippos, told The Politic about the animals’ murky origins.

“If you want to trust the documentation from the time,” Valderrama cautioned, “[Escobar] brought three pairs of hippos from different zoos in the U.S. But–because you never know with Pablo Escobar–people say he really brought three females and one male directly from Africa.”

In either case, along with dinosaur statues, tanks, and cocaine-smuggling planes, the hippos were among the attractions locals enjoyed for years at Hacienda Nápoles, free of charge. But when Escobar was killed in 1993 after a massive manhunt, the ranch was confiscated.

“Most of the animals were taken to different zoos,” Valderrama told The Politic. “But the hippos, most of them stayed at Hacienda Nápoles and reproduced freely, until, back in 2007, we got word that some very strange creatures were seen in a nearby town called Puerto Olaya.”

At Hacienda Nápoles, the hippos lived within a lake–but the ranch’s simple livestock fences never guaranteed that the animals, which can weigh over four tons, would stay in.

As David Echeverri, a biologist with the local environmental authority Cornare, explained in an interview with The Politic, “The hippos took over the lake and made it their own. It offered everything they needed–food, security, and calm. They just didn’t know that they had the whole Magdalena Medio valley at their disposal.”

And it was only a matter of time before they found out. Male hippos are fiercely protective of their mates and waters, and with one dominant bull, nicknamed El Viejo, monopolizing Hacienda Nápoles, younger males had to choose between remaining subservient or moving out.

Several male hippos, including Pepe, chose the second option–making what seems like the right decision.

“This area and its environment is almost like a hippo paradise,” said Michael Knight, a South African ecologist who has advised Colombia’s Ministry of Environment on hippo population control, in an interview with The Politic. “It’s this manna from heaven, if you think about the hippos,” he observed.

Valderrama said, “They don’t have predators here. And most of the hippo populations in Africa are controlled by drought–many of the animals die naturally because of the dryness and the lack of food and water.”

But since drought occurs far less frequently in Colombia, there are effectively no controls on the hippos’ reproduction.

No one is quite sure what effect that will have on Colombia’s river environments. But all of the biologists interviewed by The Politic noted that given their size and behavior, the hippos are bound to affect local habitats, wildlife, and people.

Jonathan Shurin, a University of California, San Diego professor currently studying the Colombian hippos’ ecological impact, told The Politic that hippos in Africa are sometimes called ecosystem engineers.

“They’re sort of amphibious, they come out at night and walk around and feed on plants on land, and then they go back into the water and just poop a lot of nutrients into the water,” Shurin said. “They fertilize things, they disturb the bottom. That has a huge effect on all sorts of aquatic and terrestrial organisms.”

Valderrama and Echeverri expressed concern about whether an unchecked hippo population would displace Colombia’s manatees, caimans, and otters.

And along with Knight, all three noted that wild hippos in Colombia posed a significant risk to humans.

“In Africa, hippos and puff adders account for the most fatalities when it comes to dealing with wildlife. So hippos are up there, and they’re dangerous,” Knight said.

Valderrama described a few “mock attacks” in which Colombian fishermen were chased by hippos. As far as he knows, no hippos in the area have killed or seriously injured anyone. There have, however, been reports of damage to crops and livestock by hippos, including by Pepe, who killed at least six calves.

Between this property damage and his attempts to attack fishermen, Pepe was deemed a threat to local residents. Still, Valderrama insists every effort was made to avoid his culling.

“We searched for a place to relocate him for over two years,” Valderrama told The Politic. “We tracked the hippo, we followed him, we baited him, we did the most we could to find a new location for this hippo. And after two years, we decided that he was too dangerous for the community, and culling was the only option.”

Animal rights groups disagreed. “It is an outrage that the same government that allows the torture of bullfighting and cockfighting is now endorsing the murder of hippopotamuses,” activist Marcela Ramirez, who led a pro-hippo demonstration in Bogotá, told the Los Angeles Times.

The uproar forced the Ministry of Environment to cancel plans to cull Pepe’s mate and calf. Knight and his South African colleague Peter Morkel were flown in to help devise a humane alternative for controlling Colombia’s hippo population.

Knight himself takes a dim view of arguments that the Colombian hippos deserve protection.

“Why would you want to be propagating a potentially alien invasive species that’s very dangerous?” Knight asked. “You have to ask from a biodiversity conservation perspective, what objective is this fulfilling? Nothing more than a zoo.”

Knight warned, “If it’s a zoo, you have to contain them. It’s fine if you want to contain them, but then you have to actually manage their reproduction.”

Which is harder than it sounds. Knight and Valderrama agree that Hacienda Nápoles, which now includes a theme park, is probably the best permanent home for Colombia’s hippos. And they are both certain that keeping males and females in separate lakes on the ranch is not an option.

“When they are in season,” Valderrama explained, “the males will try anything to get where the females are, and with one escaped male among the females, that’s enough to get them pregnant. So that’s not very secure.”

Consequently, all of the male hippos will either have to be culled–unlikely, given that option’s unpopularity–or castrated.

But these are not tame animals, and the procedure can be dangerous for the people involved.

According to Valderrama, anesthetizing adult hippos is near impossible due to their size and fat content. Hippo castration then requires invasive surgery that the animal might not survive, due to the chance of infection. And it is not cheap.

“We successfully carried out the first castration of a hippo in the wild,” Valderrama told The Politic. “We captured the animal outside of Hacienda Nápoles, castrated it, and took it back. It cost us about $50,000.”

In their 2009 report on Colombian hippo control, Knight and Morkel outlined an elaborate plan to enclose the hippos around their lake at Hacienda Nápoles, then draw them into mobile steel pens where they could be anesthetized and the males identified and castrated.

The plan is estimated to cost at least $100,000, and would require an electric fence to keep the hippos from leaving Hacienda Nápoles. “All escaped animals from the sanctuary,” the report reads, “should be eliminated.”

Valderrama confirmed with The Politic that the report’s recommendations have not yet been implemented. If they are, they are likely to face some pushback.

“Of course, people who have been affected by the hippos don’t want them around,” Valderrama said. “But people in the region–I’d say that half of the people agree with the control and half of them don’t want it, because they like having the hippos.”

It appears that some local residents have even cared for orphaned young hippos from Hacienda Nápoles in their homes, with one farmer telling Fusion, “It’s just like raising a dog. They even follow you when you call them by their name.”

Echeverri understands why people might be attached to the hippos. “They’re charismatic enough,” he said, “and they draw tourists to the area.”

Still, he argued that when allocating conservation resources, native Colombian species like jaguars and pumas ought to take precedence over the hippos.

Valderrama concurred. “To be honest, I don’t want them to be sacrificed,” he said. “But the option to do nothing is really the worst option. Because we have an active, growing population of an exotic species that can harm our wildlife and people in Colombia–that’s something that can be prevented right now, and it’s our responsibility to prevent it.”

For their part, environmental authorities are enticing the hippos to stay at Hacienda Nápoles with food like carrots and alfalfa, and they have been able to capture and sterilize some of the younger stragglers.

On a hopeful note, Valderrama remarked, “If we can find a place that will be willing to receive the animals, and maybe fund the relocations, then maybe we can solve this situation before it gets to the point of no return.”

But until then, in a country still healing from Pablo Escobar’s violence and destruction, a rapidly expanding population of hippos reminds us that the kingpin’s legacy will not easily be erased.