Updated

Texas officials planned Friday to renew warnings about pirates marauding on a U.S.-Mexico border lake after a Colorado tourist was gunned down in Mexican waters while his wife dodged bullets and raced her Jet Ski back to American soil.

Search teams combed the U.S. side of Falcon Lake for David Michael Hartley, 30, whose wife told police he was shot in the back of the head Thursday after being ambushed by gunmen on boats.

The gunmen are suspected pirates who have turned Falcon Lake, a waterskiing and bass fishing hotspot down the border from Laredo, into uneasy waters for fishermen and boaters. There have been at least five reported run-ins with pirates on the lake this year, though prior holdups had never been deadly.

Hartley's fate was unclear. Zapata County Sheriff Sigifredo Gonzalez said 29-year-old Tiffany Hartley fears her husband is dead. She circled back on her Jet Ski to rescue him but had to retreat when she heard bullets whizzing by.

Gonzalez said he had contacted the Mexican consulate to ask them to search for Hartley on its side of the lake.

"I'm not trying to place the blame on her or him," Gonzalez said. "But we've told people not to go over there, and now this happens."

Texas Parks & Wildlife Department spokesman Mike Cox said Friday that the state planned to issue a fresh warning to boaters about staying on the U.S. side of the lake. The last warning came in May, and some campers on the lake have taken to arming themselves.

Falcon Lake is a dammed section of the Rio Grande that straddles the border. The border is marked by 14 partially submerged concrete towers that mark the Rio Grande's path before the lake was created in 1954.

According to Gonzalez, Tiffany Hartley told police that the couple rode their Jet Skis for sightseeing and to take pictures of a famous church in Old Guerrero. They were riding back when they saw the armed gunmen on the boats, and immediately began racing back to U.S. waters.

David Hartley didn't make it. His wife told authorities he was shot in the back in the head; Cox said one of the boats may have crossed into U.S. waters briefly while trying to run down Tiffany Hartley.

Cox said Tiffany Hartley estimated that the shooting took place about five to six miles from the Texas shoreline where she parked and called for help.

In April, pirates robbed another group of boaters who also went to Old Guerrero to see the church. Cox said the most recent reported pirate sighting had been Aug. 31, when boaters saw gunmen riding a small skiff with "Game Wardin" misspelled in duct tape on the side of the vessel.

Cox said it appeared the pirates were trying to imitate state game warden boats they have seen patrolling the lake.

Gonzalez has previously chalked up the dangerous waters as the product of fighting between rival Mexican drug gangs.

Violence on the Mexican side of the lake has been climbing for several months, as a fractured partnership between the region's dominant Gulf Cartel and its former enforcers, the Zetas, plunged many of the area's Mexican border cities into violence.