Despite repeated promises by the New York City Correction Department to tighten security at Rikers Island, an investigator posing as a guard last month was able to smuggle in heroin, pills, marijuana, vodka and a razor blade, a city inquiry found.

The investigator carried the contraband, valued at over $22,000, through six security checkpoints used by jail employees, hiding the drugs in his cargo pants and holding a water bottle filled with vodka, the Department of Investigation said in a report released on Thursday.

The revelations once again raised questions about the city’s ability to address the widespread corruption and brutality at Rikers detailed in several critical reports by federal and local authorities as well as the news media. The Investigation Department has been urging the Correction Department for years to improve screening of jail employees but to no avail.

“Weapons and narcotics remain easily available to any inmate with funds to pay for them,” the report said.