The probe, likely to be carried out by federal magistrates, will also target the head of Puebla´s top court, Guillermo Pacheco Pulido, on suspicion that he intervened in the decision of a lower judge to issue an arrest warrant for Cacho in December of 2005. Cacho faced charges of libel and defamation.

The role of Puebla Attorney General Blanca Laura Villeda in the case will also be investigated.

The decision is the Supreme Court´s latest action after voting last September to investigate the alleged plot by Marín and local business magnate Kamel Nacif to have Cacho jailed after she named Nacif as the associate of a man accused of child pornography in her book, "The Demons of Eden." The book documents child pornography rings in Cancún.

It is unlikely that the court- appointed commission will investigate the existence of the alleged pornography rings. It will probably focus on whether Marín interfered with the judicial branch to ensure prosecution against Cacho.

In audio tapes of a profanity- laced phone conversation released in February of 2006, voices identified as Marín and Nacif discuss a plan to jail Cacho.

Nacif, who made a fortune in textiles, has since come out saying the tape was recorded and leaked by his ex-wife, who he accuses of trying to blackmail him to receive a favorable divorce settlement.

The investigation ordered by the nation´s top court is highly unusual, with the body mostly ruling exclusively on cases dealing with the interpretation of the Constitution.

However, the court ruled last September that there was sufficient evidence that Cacho´s constitutional rights had been violated to warrant a formal investigation.

After the charges were issued in December of 2005, Cacho was arrested in Cancún by Puebla state agents, who then drove her 20 hours to a Puebla jail.

The charges against her have since been thrown out.