The group said that the giant funeral pyre in which the attorney general said the Ayotzinapa students were burned to ash beyond identification simply never happened.
There is a possible case of negligence in the death of Sebastián Lerdo de Tejada
Abraham Torres Tranquilino was arrested this Sunday.
It wants to clarify what happened to alleged kidnappers after their arrest.
After a scandal erupted in 2014 amid news reports about the property, Rivera said in November that she was buying the house from the company on monthly payments with money she earned as an actress.
The two-year investigation led to the arrests of more than 400 people, some 60 indictments and US$187,000 seized. The ring extended from western border cities to San Antonio and Dallas.
Citigroup's Banamex USA unit was already under investigation by U.S. regulators for possible breaches of anti-money laundering laws.
Three out of every five convicted smugglers are U.S. citizens, according to an analysis by the Pittsburgh Tribune-Review of 3,254 federal trafficking convictions during 2013 and 2014 in federal courts in the southern stretches of Texas, New Mexico, Arizona and California.
Guatemala has sealed the border with Mexico
Representatives from the U.S. Federal Bureau of Investigation and the Drug Enforcement Administration met Mexican law enforcement officials in Mexico City on Monday to share information.