Student Daniel Chong reportedly drank urine to survive 4 days while forgotten in DEA holding cell

Updated at 3:35 p.m. ET

(AP) SAN DIEGO - The Drug Enforcement Administration issued an apology Wednesday to a California student who was picked up during a drug raid and left in a holding cell for four days without food, water or access to a toilet.

DEA San Diego Acting Special Agent-In-Charge William R. Sherman said in a statement that he was troubled by the treatment of Daniel Chong and extended his "deepest apologies" to him.

The agency is investigating how its agents forgot about Chong.

Chong, 23, was never arrested, was not going to be charged with a crime and should have been released, said a law enforcement official who was briefed on the DEA case and spoke on the condition of anonymity.

The engineering student at the University of California, San Diego, told U-T San Diego that he drank his own urine to survive and that he bit into his glasses to break them and tried to use a shard to scratch "Sorry Mom" into his arm.

His lawyer Eugene Iredale said Chong went to his friend's house on April 20 to get high and fell asleep. Agents stormed in at 9 a.m. the next day and swept him up as one of nine suspects in a raid that netted 18,000 ecstasy pills, other drugs and weapons.

He was questioned for four hours and then told that he would be released, Iredale told The Associated Press. Chong was handcuffed and placed back in a holding cell.

He remained in the 5-by-10-foot cell from April 21 until April 25, when he was taken out on a gurney by paramedics.

"He couldn't fully stretch out his arms," Iredale said. "There was no restroom facilities, no water, no food."

The only view out was through a tiny peephole in the solid door. He could hear the muffled voices of agents and the sound of the door of the next cell being opened and closed. He kicked and screamed as loud as he could.

At one point, he ripped his clothing and shoved a shred of it under the door, hoping someone would spot it and rescue him, his attorney said. He tried to dig through the walls with his handcuffed hands to get water to come out, Iredale said. He ripped away foam from the wall.

"I had to recycle my own urine," Chong told the U-T San Diego. "I had to do what I had to do to survive."

After three days, he began to hallucinate, Iredale said. The pain was so intense that he bit into his glasses and swallowed a shard, cutting his esophagus. He took the broken bits and started carving into his arm but stopped after the "S," Iredale said. His lawyer believes he was thinking of killing himself.

During the last two days, the lights went out and he spent the time in darkness.

Chong also ingested a white powder DEA agents said was left in the cell accidentally and later identified as methamphetamine.

When he was found on April 25, paramedics took him to a hospital where he was treated for cramps, dehydration, a perforated esophagus and kidney failure, his lawyer said. He spent three days in intensive care and five total at the hospital before leaving Sunday.

"The DEA's answer to this is: 'Oh, we forgot about him. I'm sorry,"' Iredale said. "He nearly died. If he had been there another 12 to 24 hours he probably would have died."

The top DEA agent in San Diego says the event is not indicative of the high standards to which he holds his employees. He said he has personally ordered an extensive review of his office's policies and procedures.

Iredale said he plans to file a claim against the federal government and, if it is denied, he will proceed with filing a federal lawsuit.