5 alleged Mexican cartel members charged in kidnapping of 4 Americans

Five alleged members of a powerful Mexican cartel were charged with aggravated kidnapping and murder on Friday in connection to the kidnapping of four Americans, and the killing of two of them, in the border city of Matamoros.

The Attorney General's Office of Tamaulipas announced the charges a day after the Gulf Cartel allegedly took responsibility for the kidnapping. The five men were found tied up near a pickup truck on Thursday morning and a handwritten note was found placed on the windshield of the truck, whose author or authors say they belong to the Gulf Cartel, the dominant organized crime group in this part of Mexico.

ABC News has geolocated that location as the same area where the U.S. citizens were kidnapped one week ago.

The note said some Gulf Cartel members were responsible for the kidnapping and killings and apologized for their actions.

"We have decided to deliver those involved and directly responsible," the note said, presumably referring to the five men found tied up at the scene.

Multiple different law enforcement agencies, along with members of the Mexican army, responded to the scene.

Police allegedly found two weapons inside the truck when they detained the five men -- an AK-47 and an AR-15 -- as well as four AK-47 magazines, three AR-15 magazines and cartridges of different calibers, according to a copy of the police report from Mexican authorities obtained by ABC News from a source close to the investigation.

Police found the men inside the truck with their hands tied with belts, along with the note, according to the police report.

Multiple sources close to the investigation said they believe the note left on the windshield to be legitimate.

Neither ABC News nor U.S. officials have been able to independently verify the authenticity of the note.

ABC News has reached out to the FBI for comment.

The four kidnapped Americans -- Eric James Williams, Zindell Brown and cousins Latavia "Tay" McGee and Shaeed Woodard -- drove Friday morning into Matamoros, in the northeastern state of Tamaulipas just south of Brownsville, Texas. McGee had traveled from South Carolina to Mexico for a cosmetic medical procedure.

Soon after crossing the border, "unidentified gunmen fired upon the passengers in the vehicle," and then put the four Americans in another car and fled, the U.S. Embassy in Mexico City said.

Mexican investigators believe the kidnappers may have wrongly believed the Americans were rival human traffickers, a source close to the investigation told ABC News.

The two survivors -- McGee and Williams -- were found Tuesday morning in a wooden house in the Lagunona area, outside of Matamoros, Mexican officials said. Williams was shot in both legs while McGee was largely unharmed, family members said.

One of the deceased was also found inside the house, and the second was found outside it, a source close to the investigation told ABC News.

During the three days they were held, the Americans were transferred to various places, including a medical clinic, in order to create confusion and avoid rescue efforts, according to the governor of Tamaulipas, Américo Villarreal.

The two survivors were being treated at a hospital in Brownsville following their rescue. The bodies of the two Americans killed were repatriated to the U.S. on Thursday.

A 24-year-old suspect arrested earlier this week in connection with the incident has now been formally indicted on an aggravated kidnapping charge, the Attorney General's Office of Tamaulipas said on Friday. The man was allegedly acting as a lookout when authorities finally located the four missing Americans.

The office also announced a homicide charge in the killing of Arely Pablo, 33, a Mexican bystander who died after being hit by a stray bullet during the kidnapping.

The alleged cartel members have been indicted in connection with the kidnapping, the Tamaulipas attorney general announced Monday.