ZAPATA -- The Mexican government said Friday it has opened a federal investigation into the reported shooting of an American tourist on a border lake plagued by Mexican pirates and strongly denied delaying action on finding the man or his attackers.
A statement from Mexico's Ministry of Foreign Affairs "categorically rejects claims to the effect that Mexican authorities are not doing enough to find" David Hartley.
Hartley's wife, Tiffany, says she and her husband were riding Jet Skis back from Mexico on Sept. 30 when they were attacked by Mexican pirates in speedboats who opened fire and shot David Hartley in the back of the head. Tiffany Hartley has said she tried to rescue him when he fell into Falcon Lake, but that she fled to U.S. waters as the pirates continued shooting.
U.S. Rep. Henry Cuellar said Friday that while no evidence has caused investigators to question her story, the disappearance is mysterious.
"My question is, OK if he had a vest, why is the body not floating? We asked the Coast Guard, if he had a Jet Ski, would that Jet Ski be floating somewhere around? Our Mexican friends have said they've been searching around, they've even used a helicopter. If you have a general idea of where that is, why is the body not floating? Why is there not a Jet Ski?"
Cuellar went on to say "the bad guys could look at the Jet Ski as an asset that they could take" and that Zapata County Sheriff Sigifredo Gonzalez "does have an eyewitness, a person that did see her coming in with a boat chasing her, so we have to rely on law enforcement officials."
Gonzalez said the investigation so far has indicated Tiffany Hartley is telling the truth.
"Our information is indicating that the witness is reliable, the witness is truthful," he said. The possibility the witness is not telling the truth "is always there, but the probability is very, very, low," he said.
Evidence corroborating Tiffany Hartley's story includes a tiny smear of blood on her life vest, Gonzalez said.
"Other evidence has surfaced," he said. "I'm not at liberty to discuss it at this time, but it does indicate that she had nothing to do with" David Hartley's death.
Falcon Lake is a dammed section of the Rio Grande, 25 miles long and 3 miles across. Pirates have robbed boaters and fisherman on the Mexican side, prompting warnings by Texas state officials, but Hartley's death would mark the first violent fatality on the lake.
The foreign ministry's statement said the federal attorney general's office has opened an investigation based on Tiffany Hartley's testimony to Mexican consulate officials in McAllen, Texas, where she lives.
In the Hartleys' native Colorado on Friday, about 100 friends, relatives and supporters rallied outside the Mexican consulate in Denver. David Hartley's sister, Nikki, said it's hard to know what's happening across the border.
"We'd like to believe good people are down there but there's so much corruption, it's hard to have much faith that what you're being told is the truth," she said. But she later said she was encouraged after meeting with consulate officials who promised an open door policy to answer family questions.
The Mexican army, federal police and state and local authorities -- using speedboats, helicopters and all-terrain vehicles -- have been searching since last week, authorities said.
Ruben Rios, a spokesman for the state prosecutor's office in Tamaulipas, said the search continues during daylight hours, but is suspended at night because of winds and waves. U.S. authorities said the search also has been hampered by threats from drug gangs.
That part of Tamaulipas state is overrun by violence from a turf battle between the Gulf Cartel and the Zeta drug gang, made up of former Mexican special forces soldiers, and both are battling the Mexican military.
Texas Gov. Rick Perry on Friday softened his "no excuses" stance on the search, saying through a spokeswoman he was "grateful" for news Mexico had stepped up its efforts, calling them "significant and very helpful."
But, said spokeswoman Katherine Cesinger, "I don't think anyone will be satisfied until a body is recovered."
Officials said crews ended their search around 5 p.m. Friday and will resume their efforts Saturday morning.
Earlier this week, Perry had said he expected Mexican President Felipe Calderon to call him within 48 hours to report a body had been found and that even the threat of drug gang violence against search crews was no reason to halt the efforts.
Gonzalez said he has sent word to the Zetas that he wants Hartley's body returned.
"We cannot arrest anybody for what happened in Mexico, we cannot prosecute on the state level anybody for what happened in Mexico. We just want a body," Gonzalez said. "I did send word to the drug cartel, the Zeta cartel in Mexico, I sent word to them unofficially. I can't tell you how but I sent word to them."