A boater made a grisly discovery Tuesday afternoon when a body was found in the Susquehanna River near Long Level Marina.

But it is not yet known if the body is that of 63-year-old Wrightsville-area boater Robert Brennan, who has been missing since Sunday, officials said.

"At this time, we can not confirm it is Robert Brennan," said Lt. Stephan Englert of Susquehanna Regional Police in Lancaster County.

Lancaster County Coroner Dr. Stephen Diamantoni the body had been in the water a number of days.

"Our best estimate is between two to four days," he said.

An autopsy is scheduled for Wednesday in Lancaster.

First responders were sent to the river just before 1 p.m. after the body was discovered about 300 feet off the York County shore.

Missing boater: Brennan went missing about 3 p.m. Sunday when the canoe he, his wife and their dog were in tipped over just downstream from the Shock Mill Bridge, a railroad bridge over the river, near the Riverfront Park boat launch near Marietta.

The wife and dog were found safe and she was treated at the scene by medics. Brennan and his wife weren't wearing life vests, officials said.

The canoe, which had righted itself, was found downstream from the park with a life vest and Brennan's wallet inside.

Crews from York, Lancaster, Dauphin and Lebanon counties searched the area of the river and its banks where Brennan disappeared on Sunday and Monday but to no avail.

— Reach Greg Gross at ggross@yorkdispatch.com.