Amid an investigation into hiring and promotion practices in New York’s Metropolitan Transit Authority, the agency’s security chief has resigned.

MTA's inspector general is currently delving into issue, according to the New York Daily News.

The security chief, Vincent DeMarino, who previously worked for New York Police Department, once proudly described how he “transformed a perceived backwater department into a modern, professional and respected force,” the Daily News reported.

His sudden resignation this month remains a mystery.

“Department employees without NYPD backgrounds bitterly claim they were shut out of promotional opportunities under DeMarino while retired cops quickly ascended the ladder,” according to the Daily News.

Read the full article here.