The faction of the Gulf Cartel known as the "Scorpion Group" was responsible for the incident. The bosses of the faction apologized to the residents of Matamoros where the Americans were kidnapped, to the Mexican woman who died during a shootout with the cartel and to the four Americans and their families.

"We have decided to turn over those who were directly involved and responsible in the events, who at all times acted under their own decision-making and lack of discipline," letter stated – adding that the individuals supposedly went against the cartel's rules, including "respecting the life and well-being of the innocent."

Drug cartels have been known to issue statements. Usually, these are done to intimidate or threaten local rivals or Mexican authorities. But at certain occasions, such as when the United States is involved, drug cartels issue statements as a public relations stunt to try to smooth over situations that could severely affect their business interests. (Related: 4 Americans missing, 1 Mexican bystander dies after shootout near Texas border.)

Kidnapping and murder of Americans brought in National Guard troops to Mexico

The incident occurred on Friday, March 3. All four Americans were shot during the kidnapping.

The faction of the Gulf Cartel known as the "Scorpion Group" was responsible for the incident. The bosses of the faction apologized to the residents of Matamoros where the Americans were kidnapped, to the Mexican woman who died during a shootout with the cartel and to the four Americans and their families.

"We have decided to turn over those who were directly involved and responsible in the events, who at all times acted under their own decision-making and lack of discipline," letter stated – adding that the individuals supposedly went against the cartel's rules, including "respecting the life and well-being of the innocent."

Drug cartels have been known to issue statements. Usually, these are done to intimidate or threaten local rivals or Mexican authorities. But at certain occasions, such as when the United States is involved, drug cartels issue statements as a public relations stunt to try to smooth over situations that could severely affect their business interests. (Related: 4 Americans missing, 1 Mexican bystander dies after shootout near Texas border.)

Kidnapping and murder of Americans brought in National Guard troops to Mexico

The incident occurred on Friday, March 3. All four Americans were shot during the kidnapping.