NAPERVILLE, Ill. (CBS) — Authorities in west suburban Naperville have opened an investigation into a complaint by a former city worker who claims human resources bosses have bullied employees, spewed derogatory language, and used drugs on the job.

WBBM Newsradio’s Terry Keshner reports a former employee wrote a letter to Naperville’s mayor and the city council, dated May 2, noting he or she was resigning that day.

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The letter accused leaders of the suburb’s human resource department of bullying, smoking pot at work conferences, and making inappropriate comments to women and minorities.

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“We take these complaints very, very seriously; and we immediately launched investigations to look into the allegations, and we’ll continue to follow up and ensure that our employees have a respectful work place,” said Naperville spokeswoman Linda LaCloche. “In this instance we have some internal investigations going on, as well as an external investigation using outside counsel.”

Chicago attorney Terry Ekl has been hired to conduct that outside investigation.

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“We have very strict policies talking about respectful workplace, and just the behavior in the workplace; and we expect all of our employees to follow those policies,” LaCloche said.