Officials are calling an area of Falcon Lake where an American man's body went missing a 'hornet's nest' controlled by the Zetas drug cartel.
The body of 30-year-old David Hartley went missing after being shot and killed near the flooded ruins of Guerrero Viejo on the Mexican side of the lake.
His wife Tiffany Young-Hartley survived the alleged attack and returned to the American side with the help of a witness whose identity is being protected.
During a Wednesday afternoon press conference with all three of the Rio Grande Valley's congressmen in Zapata, officials said the search has been complicated by the fact that Hartley was killed in an area that is a stronghold for the Zetas drug cartel.
Zapata County Sheriff Sigifredo Gonzalez said during the press conference that the American side of the lake is relatively safe but noted that the Mexican side is very dangerous.
Sheriff Gonzalez said he sent a message to the Zetas cartel that all American officials are asking for is Hartley's body -- no other questions asked.
"All we want on our side of the border is a body," Gonzalez said. "We cannot arrest anybody. We cannot convict anybody. We cannot prosecute anybody for something that happened in Mexico."
Sheriff Gonzalez said the Zetas have not replied to the message but U.S. Congressman Henry Cuellar (D-Laredo) said the search continues on both sides of the border.
Congressman Cuellar said United States has been in high levels of contact with the Mexican government, which has committed 60 soldiers, three boats and a helicopter in searching for Hartley's body.
Cuellar said an intense search was called off on the Mexican side Wednesday evening when Mexican officials received a report that their rescuers might be ambushed by drug traffickers.
The Laredo-based congressman said the search resumed on the Mexican side of the lake on Thursday morning but with no results.
Cuellar called the area where Hartley"s body went missing as a "hornet's nest" for the Zetas.
"They working under the threat of their lives," Cuellar said about Mexican search crews.
Although some Mexican police and others doubt Tiffany Young-Hartley's version of events, the three congressmen and Sheriff Gonzalez reiterated their support for her.
They said blood on her vest and an eyewitness account support her claims.
Cuellar and the others said the incident underscores the need for more funding for border security as well as a bill to allow the Coast Guard to patrol Falcon Lake, Lake Amistad and parts of the Rio Grande.