Florida boater charged in teen girl's wakeboarding death sentenced to 6 months probation

Grethel Aguila and David Goodhue, Miami Herald on Jan 6, 2026

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MIAMI — The Coral Gables man operating the boat that ran over and killed a 15-year-old girl wakeboarding behind a yacht in Biscayne Bay, pleaded guilty to misdemeanor careless boating charges Monday in Miami-Dade County court.

Carlos Guillermo “Bill” Alonso, 79, will serve six months probation and take a boater safety course in an agreement reached between his attorneys and state prosecutors. Alonso ran over Ella Adler, a student at Ransom Everglades School in Coconut Grove. She was being towed with another teen behind a 42-foot boat on a congested waterway off Key Biscayne on May 11, 2024.

In exchange for the plea, Alonso will not be formally convicted on the charges. He was facing a maximum sentence of 60 days in county jail. The agreement stipulates that if Alonso completes the probation without violations, the state will dismiss the charges, Alonso’s attorney, Lauren Ford Krasnoff, said Tuesday.

Adler’s father, Matthew Adler, read a statement in court Monday, saying his daughter “made everything more joyful, more beautiful and more connected. Our lives were centered around Ella,” the Key Biscayne Independent reported.

Matthew Adler also called for more regulations on Florida waterways, noting there are far fewer rules for people operating boats than operating cars, the Independent reported.

“Too many children are dying on our waterways. Imagine if someone proposed eliminating driver’s license insurance or accountability on the roads. It would be unthinkable, but that is the reality every day on the water,” Adler said

Alonso, of Coral Gables, was operating his 42-foot Boston Whaler when he struck Adler, who was the granddaughter of Michael Adler, the U.S. ambassador to Belgium at the time of the incident. Alonso maintained he never knew he hit the girl. The accident happened on a busy Saturday afternoon on the waterway near the Nixon Beach sandbar off Key Biscayne.

Adler had fallen off the wakeboard and was treading water when hit. The other girl being towed behind the boat also was in the water.

“Our hearts go out to the Adler family. This was a tragic accident, and of course, Bill never intended to hurt anyone that day. Bill’s decision to plead guilty was driven by his hope that doing so would cause less pain to Ella’s family and help shine a light on the Ella Riley Adler Foundation,” Ford Krasnoff said in a statement.

Also charged in the case is Edmund Richard Hartley, the captain of the yacht towing Adler and the other girl, who was not injured. Hartley was charged on May 20 with four counts of careless boating, including one count for not having a lookout to keep an eye on the girls.

He has pleaded not guilty, and his case is pending. Each count filed against both Hartely and Alonso caries a maximum penalty of 60 days in jail.

The 2017 Hanse Fjord yacht that Hartley captained is owned by Jonathan Rothberg, a biotech multimillionaire who bought a $23.5-million home off the Venetian Causeway in 2021.

Also on the yacht were Emma Roberts, then 30; Sebastian Pearce, then 21; seven 15-year-olds and three 14-year-olds. Ella was one of the 15-year-olds.

One of the girls on the boat was Rothberg’s daughter, a classmate of Ella’s at Ransom. Her 15th birthday was the day before the boat outing, according to the Florida Fish and Wildlife Conservation Commission’s initial report.

FWC investigators initially thought the incident could have been a hit-and-run. The crash was on a Saturday, and FWC officers did not locate Alonso’s vessel until Tuesday, when they found the four-engine outboard docked behind his home in the Hammock Oaks neighborhood, a gated Coral Gables community near Fairchild Tropical Botanic Garden.

Alonso’s attorneys released security camera footage shot from behind his home that showed him heading out that day on his boat, and then calmly returning later in the afternoon. His attorneys said his demeanor upon returning proved he had no idea he had just hit someone on the water.