The killing of nine Americans in Mexico highlights the brutal power of the country’s drug cartels, former acting Immigration and Customs Enforcement Director Tom Homan told “Fox & Friends First” Wednesday.

“The Mexican criminal cartels control everything on the northern border of Mexico,” Homan said.

Homan said no criminal activity or smuggling occurs in Mexico without the cartels approving the plan.

MEXICAN CARTEL MASSACRE: 9 AMERICANS, INCLUDING 6 CHILDREN, FROM MORMON OFFSHOOT MURDERED

A suspect was arrested Wednesday near the Arizona border with Mexico in connection with the deaths of nine U.S. citizens -- six children and three women – Monday who were living in a faith-based community about 70 miles south of Douglas, Ariz., investigators said.

The victims’ convoy came under fire during the day in an ambush by gunmen believed to be affiliated with a drug cartel in Mexico.

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The Agency for Criminal Investigation said in a statement on Facebook that a suspect was found in the town of Agua Prieta, right across the border from Douglas, Ariz. The suspect was holding two hostages who were bound and gagged inside a vehicle.

All the victims were believed to be members of the extended LeBaron family, who live in a religious community in La Mora, northern Mexico, a decades-old settlement in Sonora state founded as part of an offshoot of The Church of Jesus Christ of Latter-day Saints.

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“There’s more to this story than we know,” Homan said, adding that a lot of members of law enforcement and the military in Mexico are corrupt.

He said the United States must stop the demand for drugs from Mexico, but worsening violence there will lead to another border crisis.

Homan said the numbers will "explode" if Mexico can no longer be declared a "safe third country" for migrants and Mexican nationals start to seek asylum in the U.S.

Fox News’ Danielle Wallace contributed to this report.