Sportsmen in southern Texas have been pulling bass and catfish from Falcon Lake for more than half a century. A 60-miles-long "big fishing paradise" that straddles the U.S.-Mexican border, it is also a hotspot for bird-watchers, providing glimpses of species like the black-chinned hummingbird and the red-bellied woodpecker.
But now the suspected murder of a Colorado tourist, who is said to have been shot in the head as he operated a Jet Ski on international waters last week, has prompted Texas officials to renew warnings about another species that inhabits Falcon Lake -- Mexican pirates.
Search teams continued to scour the U.S. side of Falcon Lake on Monday for the body of David Michael Hartley, 30, whose wife told police he was shot in the head Thursday after they were ambushed by two boatloads of armed men. Authorities say Hartley was shot while he and his wife, Tiffany, were riding their watercraft on the Mexican side of the lake. Tiffany Hartley, 29, managed to escape the gunfire and return to the shore on the American side of the lake.
Officials at the Texas Department of Public Safety (DPS) say Hartley's apparent death marked the fifth incident since April 30 in which U.S. residents ventured into Mexican waters and encountered pirates on Falcon Lake. Prior to last week, the most recent occurred on Aug. 31, when authorities say pirates aboard a small boat with "Game Wardin" written on its side, in duct-tape lettering, tried to intercept a Texas fisherman. The fisherman, aware of warnings about pirates on the lake and recognizing the misspelling of the word "warden," managed to outrun the Mexican vessel to safety, officials said.
On May 16, five armed men boarded a boat on the U.S. side of Falcon Lake. Investigators have no additional information in that incident. Only 10 days earlier, two armed men approached a boat on the lake's northern side and demanded money, which the fisherman handed over, DPS officials say.
DPS officials are warning anyone headed to Falcon Lake to be on the lookout for vessels typically used by Mexican fishermen: boats with a large prow, a small outboard motor without a cowling and no identification numbers on the hull.
The pirates are believed to be members of a drug trafficking organization or members of an enforcer group linked to a heavily-armed drug trafficking organization that utilizes AK-47s or AR-15 rifles. DPS officials say the men appear to be using local Mexican fisherman to operate the boats to get as close as possible to American fishermen.
DPS spokeswoman Tela Mange told FoxNews.com that her agency, along with the Zapata County Sheriff's Office and the Texas Parks and Wildlife Department, continues to warn boaters to stay on the U.S. side of Falcon Lake and not to venture into Mexican waters. She said Mexican authorities are cooperating in the ongoing investigation.
"We've been talking to them since Thursday," Mange said. "[The investigation is] continuing. We're searching on the American side."
Zapata County Sheriff Sigifredo Gonzalez told Fox News on Monday that the Hartleys ventured up to 3 miles into Mexican waters to photograph ruins of a famous church in Old Guerrero. Gonzalez said a witness told authorities that one of the vessels chased Tiffany Hartley back into U.S. territory
"I think they were after money," Gonzalez said of the gunmen. "We've had similar incidents happen in April and May."
He said his office is trying to contact Mexican authorities to be granted access to the area where the shooting occurred.
"However, unfortunately, we have not seen very much action on behalf of Mexican authorities to reach the scene up there and try to look for a body," he said.
David England, superintendent of Falcon State Park, a 572-acre parcel that includes Falcon Lake, said roughly 160,000 people visit the southern Texas landmark annually to camp, swim, fish, water ski and boat, among other activities. Fishing, however, reigns supreme.
"That's what it's always been known for," England told FoxNews.com.
According to the park's website, Falcon Lake, a dammed section of the Rio Grande, is a "big fishing paradise, especially for those seeking black and white bass, catfish and stripers." There's also a mile-long, self-guided nature trail and campsites with restrooms and showers.
But a growing number of those visitors have recently asked park officials about reports of pirates on the lake, England said.
"It hits national news every day, so yeah, it's getting around," England said of reports of Hartley's murder. "Yeah, anybody that has watched the news has asked about it."
England reiterated that the park has had the same warning in effect since early May, advising visitors to stay on the U.S. side of the border. As of Monday, England said Falcon State Park had just one DPS police officer assigned to the entire facility, with another full-time officer on the way, he said. Due to the ongoing media attention to the lake since Hartley's death, England thinks visitation will go down.
"I would say it probably will affect visitation," he said. "That's my guess."
Asked if the lake is safe, England replied: "Well, it is, if you listen to the warnings to stay on the U.S. side of the lake. To my knowledge, all of these incidents have happened in Mexico or right at the line, so to speak."
The shooting has prompted several lawmakers to call for increased surveillance of the area, including one politician in southern Texas who said it has become dangerous enough to avoid altogether.
"I wouldn't do it," said state Rep. Aaron Pena, who was briefed on the pirates earlier this year. "When I go out there I have all the protection Texas can provide. But the average fisherman doesn't have that."
Pena said he has no doubt that the pirates are working with Mexico's powerful drug cartels. If they didn't, the cartels that control the region wouldn't let them operate, he said.
Texas Gov. Rick Perry said last week that the shooting highlights the need for federal government to better secure the southern border.
"It's really become substantially worse in the last 18 months with the drug cartels having almost free rein," Perry said on Friday. "This is about our citizens' -- on both sides of the borders -- safety."
Ray Walser, a senior policy analyst at the Heritage Foundation, a Washington-based think tank, also called on federal authorities to shore up border security.
"This is a situation that, all along the border, we're seeing little flare-ups," Walser told Fox News. "It's not an everyday occurrence, but this is a tragedy that really should not happen."
Meanwhile, officials at U.S. Customs and Border Protection, in a statement to FoxNews.com on Monday, wrote:
"Over the past nineteen months, this administration has dedicated unprecedented manpower, technology and infrastructure to the Southwest border. Seizures of illicit goods are up across the board, illegal crossings are down, and the Border Patrol is better staffed than at any time in its 86-year history.
"Though drug cartels are engaged in an armed, violent struggle to control shrinking drug routes and territories in Mexico, we are not, however, seeing any indications of similar violence here in the U.S.
"We will continue to work with our federal, state, local, tribal and Mexican partners to keep our communities safe."
The Associated Press contributed to this report.