Brewer had first taken that stance during a Republican gubernatorial candidates debate last week. At that time, she said illegal immigrants are "bringing drugs."
"And they're doing drop houses, and they're extorting people and they're terrorizing the families," she said then.
On Friday, she reiterated her position that the majority of those who enter Arizona illegally "are under the direction and control of organized drug cartels," The Arizona Republic reported.
Officials with U.S. Immigration and Customs Enforcement said Friday they could not provide statistics on criminal-smuggling activity.
The newspaper said FBI reports show the crime rates Arizona border towns have remained essentially flat for the past decade and statewide rates of violent crime also are down.
Jennifer Allen of the Border Action Network said she found Brewer's statements "embarrassing."
"They are so without basis or fact," Allen said. "There is more than likely a case where that has happened, but not to the extent that the governor should be making that assertion."