Mexican police say they believe the "witch" of a murderous cult of drug smugglers has been killed on orders from the group's leader, but a Texas sheriff says he suspects a ruse by the two fugitives.

U.S. and Mexican authorities have sought Sara Villareal Aldrete, a 24-year-old student at a Texas college living in Mexico, since the first of 15 victims of the cult were unearthed at a ranch south of the U.S. border last week.She was at first believed to be accompanying the reputed "padrino," or godfather, of the cult, Adolfo de Jesus Constanzo, 26. But the Houston Chronicle and Houston Post reported that police believe he may have ordered her death.

"She may have known too much. She may have been ordered killed - maybe by the padrino. We believe she could have been killed and buried in Mexico (City)," Juan Benitez Ayala, commander of the Federal Judicial Police in Matamoros, told the Chronicle.

Mexican police believe Constanzo and two companions flew from McAllen to Mexico City on April 10 and then to Miami the next day, the day 12 mutilated bodies were found on a ranch 20 miles west of Matamoros, said Benitez.

Cameron County Sheriff Alex Perez, based in this border city, said he believes Aldrete is alive, even though Mexican officials reported finding her purse, her passport and $15,000 in a Mexico City apartment.

"It just might be a put-on," Perez said. "If they did find a purse or found the passport, that may have been just a trick by Sara and Constanzo to (appear) she is dead.

U.S. authorities have arrested one man and issued warrants for two others in the growing international investigation. Mexican authorities earlier arrested four people.

Serafin Hernandez Rivera of Brownsville was arrested Monday in Houston on charges of marijuana importation, possession and conspiracy. He belongs to a family suspected of involvement in drug trafficking for at least 12 years, said Oran Neck, chief Customs agent in Brownsville.