Chatham-Kent police officers have been cleared by the province's Special Investigations Unit (SIU) in a case involving a man who became sick while in custody last November.
The 34-year-old was arrested during a drug-trafficking investigation, searched twice, and placed in a cell at headquarters.
Hours later, he started vomiting, and paramedics were called to take him to hospital, where he was diagnosed with opioid withdrawal.
The SIU says officers monitored him regularly and acted appropriately once they realized he was in medical distress.
Director Joseph Martino found no reasonable grounds to lay criminal charges.
However, Martino did flag that one officer may not have completed the required 30-minute cell checks.
He said he would be referring that matter back to the Chatham-Kent Police Service and the Law Enforcement Complaints Agency for review.