SWAMPSCOTT — A Swampscott police officer accused of dealing prescription drugs — at times on duty and in uniform — has resigned.

Thomas Wrenn, 37, resigned from the Police Department for "personal reasons" on Saturday, according to Chief Ronald Madigan.

"He voluntarily submitted his resignation," said Madigan, who declined to discuss the case further.

Wrenn's action effectively thwarts any disciplinary action by the town and leaves him entitled to regular resignation benefits, including payment for unused vacation and personal time.

Wrenn is facing federal drug charges, including allegations that he bought Percocet pills and provided drugs to others. Prosecutors have accused Wrenn of routinely using and distributing drugs for more than a year, even out in the open at local bars.

Percocet is a brand name for a form of the painkiller oxycodone, the active ingredient in OxyContin.

Prosecutors are charging Wrenn with possession with intent to distribute oxycodone.

Wrenn, a 10-year veteran of the Swampscott Police Department, has pleaded not guilty to the charges against him. He did not return a phone message left at his Nahant home yesterday afternoon. His attorney, Tracy Miner, did not return a message left at her Boston office.

With the drug charges looming, Wrenn's future with the Swampscott Police Department was already uncertain. Selectmen placed Wrenn on unpaid leave last month and had planned to hold a hearing on his employment status.

"Since (Wrenn) is no longer a police officer, there is no reason for the town to pursue additional disciplinary action recommended by (the police chief)," Town Administrator Andrew Maylor said.

Wrenn is still entitled to the same benefits any other resigning police officer would receive. That includes payments for unused vacation and personal time. What would happen to his pension benefit at retirement age is uncertain. A retirement board spokesman could not be reached yesterday.

He was arrested last month after federal authorities say he bought 50 Percocet pills from an associate, who, unknown to Wrenn, was cooperating with law enforcement. That deal allegedly took place on March 13 at the Green Tea Chinese Restaurant on the Lynnway.

Shortly after his arrest, federal prosecutors say Wrenn admitted to providing Percocet to five other people, including a former Nahant cop and four women in their 20s.

If convicted, he could face up to 20 years in jail.

Two weeks ago, a federal judge ruled that the case against Wrenn could move forward during a probable cause hearing in U.S. District Court in Boston.

Staff writer Chris Cassidy can be reached at 978-338-2526 or by e-mail at ccassidy@salemnews.com.