The murder of Rolando Armando Flores Villegas, a homicide detective for the border state of Tamaulipas, has authorities on both sides of the border searching for those responsible, to bring them to justice.

He was investigating the reported shooting death of American tourist David Hartley who was gunned down on Sept. 30.

According to the Associated Press, the Hartley probe appeared to be narrowing to two alleged members of the Zeta cartel.

National Security Expert Dave McIntyre spoke to News 3 about the message the beheading of the lead investigator is sending. He also spoke in depth of how the cartels have infiltrated into the U.S. and what he believes political leaders on both sides of the Rio Grande should be doing to combat the drug cartels.

Tiffany Hartley, David's wife, told authorities they were shot by Mexican pirates while sight-seeing on their Jet Skis on the Mexican-side of Falcon Lake.