The severed head of a Mexican police commander investigating the fatal shooting of U.S. citizen David Michael Hartley on Falcon Lake was delivered Tuesday to Mexican military in a suitcase, authorities said.

The commander, identified as Rolando Flores Villegas, was one of the investigators that family members met during a meeting last week at an international bridge near Roma, said Cynthia Young, the mother of Hartley's widow, Tiffany.

Officials said the head was delivered in the vicinity of Miguel Alemán, Mexico, across the border from Roma, Texas.

The area is known to be under control of the Zeta drug cartel, which fiercely protects the sparsely populated ranchland lining the border, as well as the Mexican side of the vast Falcon Lake reservoir.

Young said the family felt the cartels were trying to scare search teams away.

"I just think they're trying to send a statement that they don't want us there," she said. "We haven't really processed what it means.

"We really want to express our condolences and our sympathy to his family," she said. "It's just sad that this is an everyday occurrence."

Missing almost 2 weeks

Hartley has been missing since Sept. 30, when he and his wife took their personal watercraft into Mexican waters to photograph a partially submerged town.

State Rep. Aaron Peña, D-Edinburg, who has followed the case, was the first to report the grisly development via Twitter early Tuesday afternoon.

The account was later confirmed by authorities on both sides of the Texas-Mexico border, including Ruben Rios, a spokesman for the Tamaulipas state prosecutor's office, and the sheriffs of both Zapata and Webb counties in Texas.

Zapata County Sheriff Sigifredo Gonzalez said he got word of the discovery while meeting with Hartley's family in McAllen.

"It's very disheartening to see this happening," Gonzalez said. "They're just doing their job — assuming it's connected to that, of course."

Gonzalez said Tuesday that 15 boats are continuing to scour the lake on the U.S. side. He said he did not anticipate "a surge of violence against" U.S. law enforcement, noting that his officers are "always cautious."

'Moving investigation'

U.S. Rep. Henry Cuellar, D-Laredo, who said he had been briefed on the incident, said there's no timetable to when the search for Hartley's body will be stopped.

"It's a moving investigation right now," Cuellar said. "We're continuing the search. At one time, there were two helicopters and 60 people out there. ... We still haven't found a Jet Ski, or a body. ... I've talked to Mexican ambassadors, and they say they're doing everything. It's not an easy search."

U.S. investigators have been hampered by an inability to cross the border. Mexican investigators, meanwhile, have expressed fears of searching in turf controlled by Zeta drug operatives, who have a reputation of being ruthless assassins.

Denise Blaz with the Laredo Morning Times contributed to this report.

lbrezosky@express-news.net