SAN DIEGO (AP) ― Four U.S. Drug Enforcement Administration employees saw or heard a handcuffed San Diego student locked in a cell for five days without food or water, but did nothing because they assumed someone else was responsible, investigators said Tuesday.

The U.S. Justice Department’s inspector general faulted several DEA employees for their handling of the April 2012 incident that left Daniel Chong in grave physical health, cost the agency a $4.1 million settlement and led to nationwide changes in the agency’s detention policies.

The employees told investigators they found nothing unusual in their encounters with Chong and assumed whoever put him in the cell would return for him shortly. Chong, then 23, ingested methamphetamine, drank his own urine to survive and cut himself with broken glasses while he was held.

A three-page summary of the investigation does not say when the four employees encountered Chong or what they heard or saw, and the DEA wouldn’t elaborate. The agency declined to say if any employees faced consequences, calling it an “ongoing internal disciplinary matter.’’

Chong was handcuffed behind his back without access to a toilet. He has said he slid a shoelace under the door and screamed for attention before he was found covered in his feces. He said he used a shard from his broken glasses to try to carve a “Sorry Mom’’ farewell message on his arm but only managed to finish an “S.’’

Chong, a student at University of California, San Diego, was detained in a drug sweep and told after brief questioning that he would be released. Last year, he reached a multimillion-dollar settlement with the federal government over what his attorneys called a near-death experience.

The Justice Department’s inspector general found the DEA’s San Diego office didn’t have a system to track detainee movements, that holding cells were not equipped with cameras and that an employee assigned to monitor cells had many other responsibilities. Employees were not required to sign in or out of the detention area, and there were no reliable electronic entry records because the door lock wasn’t working.

There was no DEA policy or training regarding operations of holding cells at the time and no requirement that holding cells be checked at the end of each day.

The inspector general faulted three case agents ― one a DEA employee and two assigned to an agency task force ― and one supervisor who were responsible for Chong’s safety. It said the supervisor exercised poor judgment and violated DEA policy by assigning two of the agents to process evidence from the cell after Chong was found.

Investigators also faulted DEA management for launching an investigation into Chong’s detention before alerting the inspector general, a violation of DEA and Justice Department policies that they said could have hampered any criminal prosecution. The DEA is part of the Justice Department.

The DEA said Chong’s case prompted new nationwide policies for handling detainees that largely mirror the inspector general’s recommendations.

Julia Yoo, an attorney for Chong, said she was “gratified that the investigation seems to be thorough’’ but called on the inspector general to release the full report. She said Chong was still in school in San Diego and “doing well.’’