AP) — A college student picked up in a federal drug sweep in California was never arrested, never charged and should have been released. Instead, authorities say, he was forgotten in a holding cell for four days.

Without food, water or access to a toilet, Daniel Chong had to drink his own urine to survive and began hallucinating after three days because of a lack of nourishment, his lawyer said.

“He nearly died,” Eugene Iredale said. “If he had been there another 12 to 24 hours, he probably would have died.”

The top Drug Enforcement Administration agent in San Diego apologised Wednesday for Chong’s treatment and promised an investigation into how his agents could have forgotten about him.

Iredale said he intends to seek damages from the DEA, and may file a lawsuit against the government.

The incident stands out as one of the worst cases of its kind, said Thomas Beauclair, deputy director of the National Corrections Institute, a federal agency that provides training and technical assistance to corrections agencies.

“That is pretty much unheard of,” he said, noting that, in his 40-year career, he has heard of instances where people were forgotten overnight but not for days.

The U-T San Diego (http://bit.ly/JRlSr8 ) was the first to report Chong’s account.

Iredale said Chong, an engineering student at the University of California, San Diego, went to his friend’s house on April 20 to get high. Every April 20th, pot smokers light up in a counterculture ritual held around the country at 4:20 p.m.

Chong fell asleep and, around 9 a.m. the next day, Iredale said, agents swept through the house in a raid that netted 18,000 ecstasy pills, other drugs and weapons. Nine people, including Chong, were taken into custody.

Chong was questioned for four hours and then told that he would be released, Iredale said. Chong was handcuffed and placed back in the same cell, a 5-by-10-foot windowless room. The DEA said there are five cells at the facility.

The only view out was through a tiny peephole in the door. He could hear the muffled voices of agents and the sound of the door of the next cell being opened and closed, Iredale said. As the hours dragged into days, he kicked and screamed as loud as he could, Iredale said.

At one point, he ripped a piece of his clothing off and shoved it under the door, hoping someone would spot it and free him, his attorney said. Chong also ripped away foam from the wall.

Chong drank his own urine to survive. He bit into his eyeglasses to break them and then tried to use a shard to scratch “Sorry Mom” into his arm. He stopped after the “S,” the attorney said. He said he believes Chong was thinking of killing himself.

Then the lights went out. He sat in darkness until the door finally opened April 25, Iredale said.

Chong told agents that he ingested a white powder they later identified as methamphetamine. It was not clear how the powder got into the cell. Chong told them it was not his, the lawyer said.

Paramedics took him to a hospital where he was treated for cramps, dehydration, a perforated esophagus (from swallowing a glass shard) and kidney failure, his lawyer said.

Chong 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 because he wasn’t authorised to speak about the ongoing investigation.

Chong 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.

The top DEA agent in San Diego, William R. Sherman, said in a news release that he was “deeply troubled” by what happened to Chong. “I extend my deepest apologies (to) the young man,” he said.

Sherman said 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. The agency declined to say what those were.