Padilla, who authorities allege was involved in a plot to detonate a radiological "dirty bomb" within the United States, was the sole detainee in a high-security wing of the U.S. Naval Consolidated Brig in Charleston, S.C., without human contact for three years and seven months, the Christian Science Monitor reported Tuesday.
Experts familiar with the interrogation technique said it is meant to deprive the suspect of any human connections as well as senses of place and time.
"It is clear that the intent of this isolation was to break Padilla for the purpose of the interrogations that were to follow," said Stuart Grassian, a Boston psychiatrist and expert on the effects of solitary confinement who examined Padilla for his lawyers.
Psychologist Patricia Zapf, who also examined Padilla at the request of his lawyers, said she believes the suspect's psychological state should have been more closely watched during his imprisonment.
"In my opinion, it appears unusual that someone held in solitary confinement for upwards of three years would not have undergone a more thorough and regular evaluation of (his) mental state," she said.
2014: The Year in Music [PHOTOS]