The search for an American tourist reportedly shot dead on a border lake has led Texas Gov. Rick Perry to tangle with the Mexican government over the investigation and efforts to recover the body.

Perry this week urged Calderon to call him within 48 hours to update him on the hunt for the body of David Hartley, whose wife says he was shot by Mexican pirates on Falcon Lake last week as they were returning to the United States on Jet Skis. Perry's office has said it expects to talk to Mexican President Felipe Calderon on Thursday.

Perry has said he hopes the body has been retrieved by the time he gets a call from Calderon.

Falcon Lake is a dammed section of the Rio Grande that has been plagued by pirates who rob boaters and fisherman who wander into Mexican waters. Hartley's death would be the first killing on the lake.

Perry said Wednesday that Mexico needs to use every resource available to find Hartley's body and have it returned to U.S. soil.

The Mexican Foreign Relations Ministry said Mexico condemns "any act that endangers the lives of innocent citizens," saying that the country "is committed to the investigation of those acts."

The ministry's statement said Mexico has "from the first moment" been in contact with the U.S. to coordinate the search and recovery of Hartley's body, and noted that Mexican authorities have "stepped up their actions with the support of specialized personnel, boats and helicopters."

The Hartley family says Mexican authorities are not doing enough to find their relative's body. U.S. authorities are unable to investigate Hartley's disappearance because it happened in Mexico.

"As long as David's not home, enough hasn't been done," said his mother, Pam Hartley.

Tiffany Hartley has said her husband was shot in the head by three men chasing them in speedboats and that he fell off his Jet Ski and into the lake. She and several relatives took boats out onto the water of the U.S. side Wednesday to lay a wreath for him Wednesday.

"It was very emotional because I know he's out there and we just all want him back so we can give him the proper goodbye," she said at a news conference later.

Perry has told The Associated Press that if Hartley's body has not been retrieved by the time he hears from Calderon, then "we're not looking hard enough." He said Mexican Foreign Ministry Undersecretary Julian Ventura had been accommodating during talks earlier this week.

The statement from Mexico City ran counter to comments by state officials in Tamaulipas, who cast doubt on Tiffany Hartley's story in interviews with the McAllen Monitor.

The district attorney there, Marco Antonio Guerrero Carrixales, also told the paper that authorities "are not certain that incident happened the way that they are telling us."

Tiffany Hartley said she was disheartened by such comments. "I know what I know. I know what I saw," she said.

Perry said the couple was sightseeing in Mexico.

"I find it really reprehensible for anyone, U.S. or Mexican, to speak otherwise," he said.

Perry also used the incident to renew his demand that the federal government do more to secure the U.S.-Mexico border as northern Mexico sinks deeper into drug-gang violence. The violence has spread in the last few months from Ciudad Juarez, the epicenter of Mexico's drug war across from El Paso, Texas, to the Mexican side of the Rio Grande Valley, including Tamaulipas state where Hartley reportedly disappeared. Two drug gangs, the Gulf Cartel and the Zetas, are battling for supremacy there and fighting the Mexican military.

"Frankly, these two presidents (Calderon and President Barack Obama) need to get together with their secretaries of state and say, 'What are we going to do about this?'"

Hartley said she and her husband, who worked in the oil business, had been living in the Mexican border city of Reynosa before moving to McAllen, Texas, at the insistence of his company. They previously had lived in Colorado.

Perry also said he spoke Tuesday to Homeland Security Secretary Janet Napolitano's chief of staff and again asked for an additional 1,000 National Guard troops on the Texas-Mexico border, a request that has been repeatedly denied.

"How many more American citizens have to die?" Perry said.


Associated Press writers Katherine Corcoran in Mexico City, Ramit Plushnick-Masti in Houston and Ivan Moreno in Denver contributed to this report. Associated Press photographer Eric Gay contributed to this report from Zapata, Texas.