MEXICO CITY – Mexico's attorney general says investigators have found no evidence that a Mexican student who survived a Colombian military raid on a rebel camp in Ecuador had ties to the guerrillas.

But Eduardo Medina said Monday the investigation of Lucia Morett remains open.

The March 1 cross-border attack killed a top commander of the leftist Revolutionary Armed Forces of Colombia and 24 others, including four Mexican university students.

Morett is exiled in Nicaragua because of Mexico's investigation. She says she traveled to Ecuador only to learn about the guerrillas' peace proposals.

Colombian President Alvaro Uribe said in April his government suspected the Mexican students were rebel accomplices. Their families deny that.