The death of a Tennessee man whose decomposing body was discovered in a pickup truck parked at a northern New Jersey shopping center this week has been ruled a suicide.

Linden Police Lt. James Sarnicki tells The Star-Ledger that an autopsy determined the man, identified only as a 39-year-old Memphis resident, died of a self-inflicted gunshot wound.

But it's not yet known why the man was in New Jersey.

Authorities found the body Monday at a Sam's Club in Linden. A store employee had called police after a shopper reported a foul odor in the parking lot.

Police officers were seen pulling a handgun from the vehicle, a Dodge pickup that had a Tennessee specialty license plate with the word "PROTECT" on it.

(Copyright 2012 by The Associated Press.  All Rights Reserved.)