( CNN ) -- Authorities in the Tamaulipas state attorney general 's office gave conflicting information Monday over whether authorities are pursuing a pair of suspects in the case of a U.S. citizen who disappeared during a sightseeing trip on the U.S.-Mexican border in South Texas . While Luis Homero Uvalle , a spokesman for the office , told CNN the suspects are two brothers who are `` well known to this area '' -- identifying them only as `` El 27 '' and `` El 31 '' -- Ruben Dario-Rios , the chief spokesman for the attorney general said , `` We have nothing official about suspects in the disappearance of David Hartley . I do not know where that is coming from . '' Dario-Rios said the lead investigator , Rolando Flores , has not indicated that there are suspects . David Michael Hartley went missing September 30 . His wife , Tiffany , told authorities her husband was shot and killed during a sightseeing trip on Falcon Lake , which bisects the international border . On Monday , Tiffany Hartley , along with David Hartley 's mother , Pam , appeared on several morning talk shows asking for information that will help investigators find those responsible for David 's death and find his body . `` Until we have him back , it 's not final , '' Tiffany Hartley said on NBC 's `` The Today Show . '' On Sunday , the U.S. Border Patrol , the Coast Guard , and Parks and Wildlife officials were back on the U.S. side of the lake searching for new evidence in the case , Gonzales said . Mexican authorities were searching their side of the lake as well , he said . Authorities from both nations are conducting separate searches and are coordinating and holding regular meetings , State Department spokeswoman Virginia Staab said . But because the disappearance happened on the Mexican side of the border , the United States can not prosecute or make arrests in the case , the sheriff said . Tiffany Hartley was on several CNN shows Thursday recounting what happened on Falcon Lake . She also talked about her feelings about people doubting her account of the alleged attack . Hartley said on HLN 's `` Issues with Jane Velez-Mitchell ' that `` I know what I know . '' `` As long as I know the truth , God knows the truth , '' she added . `` And other than that , it almost does n't really matter to me , because I know what happened that day . '' Falcon Lake is on the Rio Grande in Zapata and Starr counties in South Texas . The U.S.-Mexican border runs through the middle of the lake . Rep. Henry Cuellar , D-Texas , says 60 Mexican personnel , three boats and a helicopter have taken part in the search . Despite the dangers on the Mexican side of the lake , Texas officials on Thursday said that the U.S. side of the body of water remains safe . `` It 's is just as safe now as any other time . However , there is a threat , '' said Rep. Ruben Hinojosa D-Texas . CNN 's Justine Redman , Nick Valencia , Dave Alsup and Matt Smith contributed to this report .
NEW : Mexico authorities give conflicting accounts over suspects . Tiffany and Pam Hartley appear on several talk shows Monday . David Michael Hartley disappeared September 30 after pirate attack , wife says .