The academy's principal Yuval Kahan will only be questioned on suspicion of negligent homicide.
Manslaughter attributes the results of an offense to indifference or recklessness, while in negligent homicide cases, the suspect is believed to not have been able to foresee the outcome.
The instructor and the principle were arrested soon after the disaster, which claimed the lives of ten teenagers who were supposed to begin attending the academy in the fall. The suspects' remands were extended after police identified contradictions in their answers to investigators' questions about the trip's planned route.
Kahan's lawyers said in a statement on Sunday, "Yuval is in agony and his heart is torn because of the terrible disaster and the loss of lives of the teenage girls and boy—his students and future students. Our position is that it would not be right at this time to comment on the different reports in the media.
"We will only stress that these reports do not reflect things as they are. Yuval is fully cooperating with investigators out of an honest desire to allow law enforcement authorities to examine the matter thoroughly and reach the truth," the lawyer said.
State Comptroller Yosef Shapira instructed his staff Sunday to prepare for a thorough inquiry in the wake of the Aravah flash flood that claimed the lives of ten teens, and that sparked harsh criticism of the conduct of the education and defense ministries.