Inset: Leslie Pope (Port St. Lucie Police Dept.). Background: The Cleveland Clinic Tradition Hospital, where Pope worked as an ICU nurse (Google Maps).

A 54-year-old ICU nurse in Florida is accused of stealing fentanyl from a "critically ill patient" after she was allegedly seen using a syringe to draw the drug from the victim's IV and then placing the syringe in her pocket.

Leslie Ann Pope was arrested on Oct. 8 and charged with three felonies, including grand theft of a controlled substance, possession of a controlled substance without a prescription and fraudulently obtaining a controlled substance, authorities announced.

According to a news release from the Port St. Lucie Police Department, the case centers on two encounters at Cleveland Clinic Tradition Hospital on June 24 and 25.

A family member told investigators they saw Pope "use a syringe to withdraw fluid from the patient's fentanyl infusion, place the syringe in her pocket, and leave the room," the release states. Investigators emphasized that Pope was not assigned to that patient's care.

The following evening, Pope allegedly returned to the same patient's room and approached the IV equipment. Detectives reviewed surveillance footage from the room that allegedly showed Pope "manipulating protective caps on the equipment" before the family member intervened. It was unclear whether additional medication was removed from the IV during that second encounter.

"That's not standard procedure, from what I understand at the hospital," Brittany McNally, the public information officer for the Port St. Lucie Police Department, told Tequesta, Florida, ABC affiliate WPBF, referring to Pope allegedly removing fentanyl from the patient's IV. "But again, she's not even assigned that patient. And there was no initial justification for her to even be in that room at the time."

Police said they examined hospital recordings and medical and administrative records, reviewed medication transactions, interviewed witnesses and coordinated with the Drug Enforcement Administration.

"The patient was on a specific monitor for the situation that he was in the ICU," McNally told WPBF. "And this individual had this monitor that had video recordings, which was a key piece of evidence in this case and completely contradicted what her recollection was."

Following her arrest, Pope denied unlawfully taking any drugs from patients or using drugs for personal consumption, according to McNally. However, police said they have "an overwhelming amount of evidence to prove otherwise."

A Cleveland Clinic spokesperson told the station that Pope no longer works at the hospital and that the facility is cooperating with law enforcement. The spokesperson declined to comment further, citing the ongoing nature of the investigation.

Pope was booked into the Palm Beach County Jail on an out-of-county warrant Oct. 8 and released Oct. 10 after posting a $150,000 bond. It was not immediately clear when she was scheduled to appear in court.