MATAMOROS, Mexico (NewsNation) — Authorities in Mexico announced the arrest of five people on Friday in connection with an attack that left two Americans dead.

The suspects were arrested in connection with a kidnapping and homicide investigation, according to Tamaulipas Attorney General of Justice Irving Barrios Mojica.

It’s not clear if the suspects who were arrested were the men left handcuffed — purportedly by Gulf Cartel members — with an apology note for the killings. The note was signed “Scorpions,” the name of a separate faction.

Initial reports claimed the Americans were traveling down to the area for a medical procedure.

But new information has raised questions about a possible connection between the Americans and the kidnapping.

Mexican law enforcement agents said they were investigating the possibility that members of a drug cartel kidnapped the Americans thinking they were encroaching on their turf, according to an internal government document seen by Reuters.

The bodies of the two Americans killed were finally repatriated to the United States Thursday. The family of victim Shaheed Woodard broke their silence after his death.

“It’s just so hurtful to see the video and how he was drugged and thrown on the back of the truck…just being helpless, not to be able to do anything,” James Woodard, father of Shaheed Woodard, said.

Mexican sources told NewsNation that the Gulf Cartel is in charge of the region and has turned Matamoros into part of a key drug trafficking route for the distribution of cocaine.

Mike Ballard with the security firm Global Guardian says the Gulf Cartel over the years has become fractured and divided, leading to the formation of factions like the Scorpions, who don’t always have a clear leader.

“What you see now is a more flat organizational structure,” Ballard said. “They’re like cell types.”

Former Border Patrol sector chief Victor Manjarrez says ever since the U.S. and Mexico started going after cartel leaders — what’s known as the “kingpin” strategy — less organized cartels have taken hold.

The Gulf Cartel is a prime example — last year the head of the group, “El Contador” or “The Accountant,” was indicted by U.S. officials.

The boss before him was taken down in 2012 and is sitting in U.S. prison. The result is a power vacuum — which becomes dangerous.

There has been a large, heavy police presence since the incident. Two men were arrested earlier Wednesday in Matamoros and brought in for questioning. It’s unknown if those arrests are connected to the kidnapping case.

Reuters contributed to this story.