The body of a Prairieville boater who has been missing on Bayou Manchac since Monday night was found Friday morning about a mile downstream from where his small bateau ran into trouble nearly four days earlier.

State Department of Wildlife and Fisheries agents and Ascension Parish sheriff’s deputies found Allen Fitzgerald, 23, about 8:05 a.m. Friday, officials said in a statement.

His discovery brought to a conclusion days of intensive searching by a variety of parish and state agencies that used a helicopter, sonar pulled by boats and the dragging of the bayou bottom in attempts to find the missing man.

The body’s location just downstream from where Fitzgerald’s boat began taking on water but still 3.5 miles upstream from where the 12-foot bateau ended up led state wildlife agents to suggest that Fitzgerald somehow got out or fell out of the boat.

Maj. Cliff Comeaux, who is a regional supervisor in state wildlife’s Enforcement Division, suggested the boat may have then continued to float unoccupied and unseen in the dark Monday night once Fitzgerald was out of the boat.

The boat wound up in the Amite River about 5 miles from where the problems started Monday. Bayou Manchac flows into the Amite.

Fitzgerald and another man had been traveling in the bateau on the bayou Monday in Ascension about 3 to 4 miles upstream of the Amite when the boat began taking on water about 9 p.m., state wildlife officials have said.

Fitzgerald’s passenger, who was in the front of the boat, jumped in the bayou before the bateau sank, but Fitzgerald remained in the back of the boat, the officials said.

Fitzgerald’s passenger made it to shore and found a house where he called 911 for help.

Comeaux said Fitzgerald had instructed his passenger to jump out because the boat began taking on water but added that authorities may never find out why Fitzgerald did not jump out or under what circumstances he was able to get out later.

Gabe Giffin, state wildlife spokesman, did note that the boat had a fixed canopy over it and when boats with such canopies roll over, passengers can get trapped inside.

Neither Fitzgerald nor his passenger had been wearing life jackets, wildlife officials said.

The two were also on the bayou after severe rain storms early on Monday had briefly subsided, but they had been caught in rain on the Amite later that evening at one point before heading back in a boat with a small, 6-horsepower engine against strong currents.

Wildlife officials had noted earlier this week the high water on Manchac had made the search for Fitzgerald more difficult.

Authorities began searching 10 p.m. Monday for Fitzgerald and stopped about five hours later, waiting for daybreak Tuesday.

The search continued all day Tuesday, Wednesday and Thursday and again Friday morning.

Agents with the state Wildlife and Fisheries Enforcement Division and the Ascension, Livingston and East Baton Rouge parishes sheriffs’ offices; and the St. Amant and Galvez fire departments had been a part of the search.

Follow David J. Mitchell on Twitter, @NewsieDave.