GIBSONTON — Three-year-old August Morris was on an island, alone, when his dad's cellphone rang.

William "Billy" Morris III had called his wife, Tina, earlier Monday afternoon to let her know he and "Augie" had pulled their Sea-Doo water scooter onto this spot in the middle of the Alafia River just west of Interstate 75, deputies said. Morris said they'd be home soon.

When they didn't show up, Tina Morris called back about 5:45 p.m., using the video application FaceTime. She expected her husband to pick up. Instead, Augie answered, crying.

Dad was gone.

Authorities scanned the river until about 11:30 Tuesday morning, when a search party on a Hillsborough County Fire Rescue boat spotted a body lying on a sandbar amid a mangrove along the south bank of the river, just east of the U.S. 41 bridge and about a mile west of the island.

Investigators believe it's Morris, Hillsborough sheriff's Col. Chad Chronister told reporters gathered at a nearby boat ramp. The medical examiner will confirm the identity and determine a cause of death, but foul play is not suspected, Chronister said.

"Unfortunately, it wasn't the outcome we desired, but at this point at least the family can get some closure about what we believe is a tragic accident," Chronister said.

Exactly what happened to the 38-year-old father of three remains a mystery.

Earlier in the day, before his body was found, Morris' family was anxious and puzzled about his disappearance. They wondered how he got separated from his son and cellphone.

"I just don't understand the whole scenario," said Morris' mother, Cindy, in a phone interview. "It's not like him to leave everything."

Morris was a trucker for a company that hauls goods throughout Florida for Amazon and is usually on call, so he always keeps his phone with him, his mother said.

Cindy Morris wasn't surprised that Augie, who turns 4 in January, knew how to answer the phone.

"He's a smart little cookie," said Cindy Morris of Gibsonton.

Billy Morris and the boy left their canalfront home on Oak Street, on the north side of the river east of U.S. 41, about 3:30 p.m. Monday, said sheriff's spokeswoman Debbie Carter.

They stopped at the spot in the Alafia that locals call Island 75 because of its proximity to the interstate. It has a small, sandy beach and is a popular stop for boaters and water scooter riders.

When Tina Morris made her call, she kept her son on the phone while she contacted the Sheriff's Office. About that time, a man on a water scooter spotted the boy and stopped to stay with him until deputies arrived, Carter said.

They found the Sea-Doo pulled up on the island's southern bank with Morris' wallet and an adult-sized life jacket nearby, but Morris was nowhere to be found. Augie was in good health and did not require medical treatment, but his youth prevented him from giving investigators an account of what happened, Chronister said.

The Sheriff's Office launched a search Monday evening with the help of Hillsborough Fire Rescue and the Florida Fish and Wildlife Conservation Commission. Called off overnight, the search resumed after sunrise Tuesday. A helicopter made low passes over the river near the island as divers searched below the surface.

About 11:30, Sheriff's Office personnel who had been searching near the island activated their boat lights and sped west, toward U.S. 41. Morris' body had been found, pushed west by the current and strong winds.

No one answered at the Morris' coral-colored, two-story home Tuesday afternoon. A life jacket hung from a railing and a pumpkin sat on the front stairs. A friendly-looking ghost decoration on the door greeted visitors.

A woman who identified herself as a friend of Cindy Morris answered her phone there and said Morris wasn't able to talk.

In an earlier interview, Cindy Morris said Billy was one of two brothers and grew up in the Gibsonton area, spending lots of time fishing and waterskiing with his father, Bill Morris II. The elder Morris, who died this past Easter, was an elephant owner and trainer, and he and Cindy toured the country with their Elephant Encounter show.

Billy Morris bought the home where he lived about a dozen years ago, his mother said. He's been married to Tina for about eight years and has two sons, 18-year-old Bill IV and Austin, 8, from a previous marriage.

Calling her son "good-hearted," Cindy Morris struggled to cope with the prospect of another loss after the sudden death of her husband.

Her voice breaking, she said, "It's been a hard year."

Times senior news researcher John Martin contributed to this report.