LAPLACE — An alert area resident helped authorities locate a vehicle directly connected to a fatal shooting investigation that spans at least three parishes.

St. John the Baptist Parish Sheriff Mike Tregre said a motorist noticed a G.M.C. Sierra oddly sitting in a Belle Pointe Subdivision sugar cane field early Monday.

When the vehicle did not move for several hours, the police were notified, and authorities eventually determined it belonged to Ryan Joseph Dubuc, a 20-year-old man found dead in Hahnville.

Dubuc, who lives in Metairie and works in Waggaman near the parish line between St. Charles and Jefferson, left for work at approximately 5:30 a.m. Monday, authorities said.

He was found dead with several gunshot wounds a few hours later as the St. Charles Parish Sheriff’s Office was notified of a body on a side road near Highway 3160 in Hahnville at approximately 9:45 a.m.

St. Charles Parish authorities initially asked for the public’s help Monday afternoon locating Dubuc’s vehicle, described as a 2006 gray G.M.C. Sierra with possible window damage. By 8 p.m. Monday, authorities announced they located the vehicle in LaPlace.

Tregre said authorities with St. John and St. Charles were conducting a complete canvass Tuesday of the area surrounding the Belle Pointe Subdivision sugar cane field where Dubuc’s vehicle was discovered.

Corporal James Grimaldi of the St. Charles Sheriff’s Office said authorities are looking for a person of interest, described as a black male standing approximately 6 feet tall. Grimaldi said a man fitting that description was seen between 7 and 8 a.m. Monday near Dubuc’s truck in LaPlace.

According to Grimaldi, detectives believe robbery was the motive for Monday’s killing; however, they are unaware if the victim was specifically targeted.

The St. Charles Parish Sheriff’s Office is urging anyone with information concerning the killing to contact Detective Thomas Plaisance at 985-783-1135 or 985-783-6807.