Los Angeles (CNN) -- A San Diego college student filed a legal claim Wednesday for damages suffered when he was left handcuffed and without food or water in a Drug Enforcement Administration holding cell for five days last month.
A DEA statement said Daniel Chong, 23, was "accidentally left" in a holding cell.
"Accidentally? He almost died," said Chong's lawyer, Gene Iredale. "It's inexplicable."
Chong drank his own urine to survive as his cries for help were ignored by federal agents and inmates in nearby cells, Iredale said.
The fifth-year engineering student at the University of California, San Diego, was detained on the morning of April 21, a Saturday, when DEA agents raided a house they suspected was being used to distribute MDMA, commonly known as ecstasy.
A multi-agency narcotics task force including state agents detained nine people and seized about 18,000 MDMA pills, marijuana, prescription medications, hallucinogenic mushrooms, several guns and thousands of rounds of ammunition from the house, the DEA said.
Chong admitted going to the house "to get high with his friends," the DEA said. He later told a San Diego TV station that he knew nothing about the other drugs and guns. He was never formally arrested or charged, the DEA said.
The agents sent seven suspects to county jail and released another person, but Chong "was accidentally left in one of the cells," the DEA said. The agency did not explain how he was forgotten for five days in the small, windowless cell.
It wasn't until the afternoon of Wednesday, April 25, that an agent opened the steel door to Chong's cell and found the handcuffed student, Iredale said.
"Even if they forgot him for the weekend, there is no account for how they could have left him there for three full business days," Iredale said.
The acting special agent in charge of the DEA's San Diego office said he was "deeply troubled" by the incident and he offered his "deepest apologies" to Chong.
"This event is not indicative of the high standards that I hold my employees to," William Sherman said. "I have personally ordered an extensive review of our policies and procedures."
On Wednesday, Iredale filed a damage claim with the DEA, which he said is the beginning of the process for a civil suit in federal court.
"He began hallucinating sometime around the end of the second or start of the third day," Iredale said. "At some point, he wanted to kill himself because of pain."
Not knowing why he was being kept in the cell without food, water or a toilet for so long confused him, Iredale said.
He lost track of time in the dark cell, his lawyer said. "At the end, he just wanted to die because he was crazy."
Chong contorted himself to shift his handcuffed arms from behind his back to the front, Iredale said. This allowed him to use his eyeglasses to scratch a message to his family on his arm: "Sorry mom."
He was rushed to a hospital, where he was kept in intensive care for two days, having been close to death from kidney failure, Iredale said.
The Cerritos, California, native is now recovering at home, he said.
CNN's Lindy Hall contributed to this report.